gman1971

Glad that is working out for you.
For other possibilities:
For most of my use cases with GMRS, I am running some sort of Motorola radio. So I end up using lip mounts with a NMO (New Motorola) base, and a Laird 1/4 wave 6" long antenna. they are fairly discrete, yet still get out well when mobile. 
Shown in my picture is a magnet mount Laird GB8UM with mini-UHF connector (for mobile Motorola radios), and a Laird QW450 (to 470MHz) antenna that works very well with GMRS in the 462-467 MHz spectrum. 

Asstated GMRS is in the middle of the business band. Most any UHF 450-470 antenna will perform fine. 

nanoNVA is better for trimming antennas anyway 

So first where is your antenna for the 275 ? I run the midland in both my JT and JK and have no issues. Do you have after market LED lights (headlights) by chance. on my JK ii bought ebay LED lights and it killed the 2 mtr band completely. 
 

TM-V71a is a nice radio, indeed, and the install seems top notch; but I will point out that the TM-V71a doesn't have a particularly selective receiver, that is if selectivity is what the OP wants.
CDM1550, those can be found < 100 bucks in near mint conditions. can be remote mounted.
XPR4550, fairly good receiver, can be remote mounted.
Obviously, the XPR5550e, which can also be remote mounted, but that one is more expensive.

Unicorns... LMAO

All those radios are basically modified ham gear. There should be no reason why GMRS radios couldn't have great filtering, as they only need to listen to a handful of frequencies... but again, any filtering just piles on the cost... and we all know that everything these days needs to be free... 
G.

I used to be responsible for a fleet of AN/TRC-170 Troposcatter terminals, 6600 Watts would drop birds and kill trees (including pine trees) in the distance when used in Line of Sight (LOS) mode. At Timberline Lodge, I would rope off half the parking lot, and then see my signal drop when some fool would run over the flagging tape, knock over a dozen traffic cones and park their larger than school bus sized recreational vehicle right in front of my "Mickey Mouse Ears" antenna system. SatCom was a lot easier in that regard. After a week, there would be a path of dead birds and brown/red conifer tree in the distance....I did not like working LOS mode with those terminals. (Smarter birds would leave the area, it was always the robins and finches that were found dead, no eagles or crows.)
Living in a pine forest then resulted in the development of UHF satellite communications, because, as you mentioned VHF has become saturated in many areas. VHF is cheap, but abundant, and I see that as well with UHF. UHF is also saturated (partially due to the proliferation of CCR's), and so is 900 MHz ISM band frequency hopping radios, as they were sold to every office and construction company in the region. That is also why I added a DTR410 to my suite of radios that I use to monitor local comms. 
All of this is driving many users to higher end and more selective radios though, which I see as a good thing. For GMRS, antenna height and quality can help, but so can a better radio. My minimum is Motorola CDM1550LS+ mobiles and HT750/1250 handhelds (but would use CDM1250's for mobiles if I owned any). It is all about the system or package, which can result in the system becoming more than its parts, if a person does not cheap out or cut corners. While CCR's may get people into the hobby, better gear will help, as will height and quality coax and antennas.
Some of these forums have made me laugh with the justification of some of the worst RF emitters I have ever experienced, or lack of grounding, or lack of lightening protection with antennas/coax/towers/push up pipes connected to houses that would burn to the ground in a lightening strike. Pay attention to details, as those details may come back to bite you.....or you may get lucky and never have a problem.

Radio waves coming from the antenna are just like the light coming from a flashlight. If you light it up atop of a lighthouse, someone will be able to see your light from tens of miles away, now, if you light up the same flashlight at ground level, it won't be seen from very far away at all.
Repeaters are like lighthouses, they are placed high above the ground.
G.

What lesser expensive GMRS built radios do this ? I have yet to find a GMRS mobile that was designed as a GMRS mobile other than Midland. All other are a CCR radio that has firmware to lock it in a band or frequency range. You can buy the same radio with different model numbers ie: DB-20=Anytone779, KG1000G=KG1000M=KGUV980....
Guess I don't understand the dual mode statement. Scan allows you to monitor other GMRs channels. If you meant other uses (Amatuer, MURS, Scanner) then it wouldn't be a GMRS radio.
I have no need for a MTX500 as I already have the MTX275 so am not going to order one to run checks on my service monitor. When the new 575 comes out I may upgrade one of mine and run some tests to see what it shows. If I need 50 watts I'll use my APX, but have yet to find a reason to. 
I find it strange that people get all worked up over Midland charging a few $ more for a GMRS only radio but no one mentions Motorola T800 series that cost about $130 a pair and can't use repeater splits nor have removable antenna's. Walk around any campground or park this summer and you will find talkabouts all over....Its all about how folks use the radio. Many just push and talk. Simplex is the most likely the most used mode in GMRS so Midland, Motorola and other manufacturers will cater to that before they worry about the 300 users on mygmrs.... 

Absolutely, Superheterodyne is nowadays a marketing buzzword; and with that said, superhets of old used to be really good, b/c they spent a lot of time/effort in making them work very well because there wasn't any other practical way to do it... Heck, if done well, those can be quite amazing.... in fact, a member from another forum shared with me some data, showing that the best selectivity he's ever measured was in a double conversion superhet radio made in 80s... I'll have to find the PM somewhere for the model, but yeah, superhets can be made extremely well. 
But I also agree that DSP and SDR radios are the way forward. The XPR7550e uses basically a direct conversion architecture. However, they have something inside that radio that no other radio can, short of the APX radios, can top in terms of performance. Its probably filtering coupled with DSP and who knows what else... 
A lot of the Icom radios like the 7300, etc, all seem to use direct conversion SDR, and those are nothing but amazing radios, I would love to own one when cash allows, but if you look at the crazy filtering they use in those radios is just insane... heck, even tracking filters, and those are not cheap... and the radio price tag shows, 3500 and 13000 for the two top performers in the Icom HF base rigs catalog... I bet most that of the price tag was due to the impressive filtering and DSP-wizardry stuff... otherwise it would be no different than the 29 dollar SDR POS running some SDRsharp on Windows.
Well, the oversimplistic superhet and oversimplistic SDR are the ways of the CCRs, they took the basic SDR and surrounded in a case with a screen and an antenna, or they got some reference design from all these radios made in China, and made it as cheap as possible, and once again, shoved it inside a fancy box with a fancy screen and sells them for x100 the price it costs to make... 
Sometimes, going to a "blank piece of paper" is the only way to go. If you take someone else's design you are also taking all the assumptions and design factors that went into that design, which might work in the short term, but once you start iterating, you'll certainly bump into those; and the end result is that to meet deadlines you'll resort to hacking everything together, again, been there done that.
Weeeell.... not sure if "Front end improvements" are as easy to implement as the "throw some improvements there" makes it feel like it is; those are rather expensive, and time consuming, otherwise the ICOM IC-7810 would go for 130 bucks, and not for 13,000 dollars, I would think. I also suspect the IC-7810 has its own custom everything, they probably scrapped a lot of stuff from the previous generation radio designs just to get that extra performance they needed, just like I've done before in my career, because hacking the previous design just wasn't going to cut it.
G.

Ah, the good old ISO-tee test... special thanks to repeater-builder.com for putting information on how to perform the procedure.
"I am a simple man with a directional coupler... only an ISOtee away from the truth."
G.

Radio waves coming from the antenna are just like the light coming from a flashlight. If you light it up atop of a lighthouse, someone will be able to see your light from tens of miles away, now, if you light up the same flashlight at ground level, it won't be seen from very far away at all.
Repeaters are like lighthouses, they are placed high above the ground.
G.

Absolutely, Superheterodyne is nowadays a marketing buzzword; and with that said, superhets of old used to be really good, b/c they spent a lot of time/effort in making them work very well because there wasn't any other practical way to do it... Heck, if done well, those can be quite amazing.... in fact, a member from another forum shared with me some data, showing that the best selectivity he's ever measured was in a double conversion superhet radio made in 80s... I'll have to find the PM somewhere for the model, but yeah, superhets can be made extremely well. 
But I also agree that DSP and SDR radios are the way forward. The XPR7550e uses basically a direct conversion architecture. However, they have something inside that radio that no other radio can, short of the APX radios, can top in terms of performance. Its probably filtering coupled with DSP and who knows what else... 
A lot of the Icom radios like the 7300, etc, all seem to use direct conversion SDR, and those are nothing but amazing radios, I would love to own one when cash allows, but if you look at the crazy filtering they use in those radios is just insane... heck, even tracking filters, and those are not cheap... and the radio price tag shows, 3500 and 13000 for the two top performers in the Icom HF base rigs catalog... I bet most that of the price tag was due to the impressive filtering and DSP-wizardry stuff... otherwise it would be no different than the 29 dollar SDR POS running some SDRsharp on Windows.
Well, the oversimplistic superhet and oversimplistic SDR are the ways of the CCRs, they took the basic SDR and surrounded in a case with a screen and an antenna, or they got some reference design from all these radios made in China, and made it as cheap as possible, and once again, shoved it inside a fancy box with a fancy screen and sells them for x100 the price it costs to make... 
Sometimes, going to a "blank piece of paper" is the only way to go. If you take someone else's design you are also taking all the assumptions and design factors that went into that design, which might work in the short term, but once you start iterating, you'll certainly bump into those; and the end result is that to meet deadlines you'll resort to hacking everything together, again, been there done that.
Weeeell.... not sure if "Front end improvements" are as easy to implement as the "throw some improvements there" makes it feel like it is; those are rather expensive, and time consuming, otherwise the ICOM IC-7810 would go for 130 bucks, and not for 13,000 dollars, I would think. I also suspect the IC-7810 has its own custom everything, they probably scrapped a lot of stuff from the previous generation radio designs just to get that extra performance they needed, just like I've done before in my career, because hacking the previous design just wasn't going to cut it.
G.

Radio waves coming from the antenna are just like the light coming from a flashlight. If you light it up atop of a lighthouse, someone will be able to see your light from tens of miles away, now, if you light up the same flashlight at ground level, it won't be seen from very far away at all.
Repeaters are like lighthouses, they are placed high above the ground.
G.

MURS is license by rule like FRS and CB, but not GMRS. GMRS requires a user to obtain a license.

A good radio will always be a good radio. The HT1000 is one of those good radios, rugged and with a decent receiver... obviously no screens nor none of these fancy bells and whistles we have on radios today, but the receiver was very decent. I remember seeing these used all over the place in the 90s.  I still use CDM radios for light duty repeater application. Radios in the past used to be built to last a lifetime... nowadays, everything has been "forced obsolescence..."
G.

MURS can also be used for data transmissions AFAIK...
@marcspazthat is my understanding as well.
G.

Engineering and testing costs go up as everything else does. Add in manufacturing costs, shipping and every other thing involved in communications. It all adds up. Competition does change the price model but for certain items all vendors are in the same ballpark. Its not just radios. Its every piece of gear a FF or LE/EMS unit use. Heart monitors, ambulances, weapons, air packs all cost more every year. Its the price of doing business in some aspect. I dont have the answer but I definitely agree you get what you pay for....in all things.
 
Oh and our SAR team still uses HT1000's that are way obsolete but they do what we need. We do have a mix of APX and XTS also but the HT is the go to radio for a field team.
 

@wayoverthere
Totally agree. I am certain each certification costs money. And some people when they see a Part95a radio they will just run for the hills...
G.

I posted this on another forum, but I figured it might be helpful to post it here as well. This is a comparison of some of the top of the line radios in the LMR/LEO market. Including the mighty APX8000, and the HT1250 from the 20th century...  Added the Astro Systems Saber
UPDATED: Feb-22-2022

My first GMRS radio...

My current GMRS radio... 

G.

Yeah, the 8000 is in a class of its own... with a mighty impressive price tag too...

Yeah, the 8000 is in a class of its own... with a mighty impressive price tag too...

Quality Control and Manufacturing Tolerance. I know of a corporate site that bought many different Midland products to support work and office operations in two buildings that take up about one square city block. They noticed the same thing, and boxed up the radios that did not work as well as others. Many of these were Midland T7x series handhelds, and we had to break the fixed antenna off to test them with Aeroflex and Hewlett Packard/Agilent Technologies test equipment. Their performance was all over the place. Receive sensitivity and selectivity was anywhere from about 0.27uV to 0.50 ish uV (most being toward the 0.50 uV end of the scale).....for UHF 0.35uV is considered "good" by many. 
In your case, there could be other issues as well, being mobile radios, as the antenna connectors could be better/worse, bends in the coax and the center conductor to sheathing/ground, quality of coax, ground plane around antenna. Lots of factors. Even power from the vehicles could impact range, power output, and radio function. You can take piles of Midland MXT275 radios, place them into  the same make, model, and year of vehicle, and still get some variance based on many factors. The more of those factors that are the same, the easier it is to narrow down.
A co-worker of mine, installs Motorola XTL1500 mobiles into Chevy Suburbans, same make, model year, and places the antennas int he same location. He still has some variation in function, but much less deviation due to manufacturing tolerances and quality control. A thousand dollar radio is usually built better than one that costs only a few hundred. Couple that with better coax, a quality antenna, and install it with attention to detail, and it will outperform a cheaper model.
Likewise, two different installs of the same equipment can have variations based upon that installation. Are the coax connectors soldered or crimped, is the ground braid even around the connectors, are there any tight bends or twists, is there a coil of extra antenna cable at either or both ends (radio and antenna if applicable), what is the output power to the radio (12v -13.8 VDC), was the radio made at the end of a shift, where was it made, etc.