What range does your multimeter read? Some of my coworkers tell me that a circuit is open, then I find they are using meters that only read up to 6k ohms and the circuit was a 10K ... wasn't open, but their meter couldn't tell
Some Nagoyas are counterfeits made in China. If you got a genuine Nagoya that isn't superior, that is unusual.
Contacts made thru repeaters are often poor for comparisons because repeater antennas are often mounted much higher than is practical with HT or mobile units AND repeater receivers are dramatically better radios than HT's.
A much better test is simplex HT to HT.
This. You have to buy radios and use them or there is no traffic on the band. Be one of the few - next thing you know, you will be one of some, then one of many.
I have an older mono 50 watt Alinco I bought used just because new 1.25's with decent power are hard to come by. Don't skip it just because you can't buy new
Stopped in less than 5 minutes of his hour long video when he said power can overcome line of sight. If you want to be taken seriously you just CANNOT tell people this.
Unless your current coax is making significant loss, changing to lower loss coax isn't going to make a difference in your TX distance. Elevation is the place to spend your money. (Fars and moneys in Randyspeak. I don't know the proper Randyspeak term for elevation; might be highs, talls or ups.)
But it is more likely to apply more of its radiated power on receivable center frequency and less wasted on harmonics that no one hears. Your money is not wasted.