As said your radio is narrowband and some users are on wideband hence making the voice lower. I've used the 275 in all my off road vehicles since they hit the market. Folks on this site complain about midland non stop but they are the only GMRS only radio in the market. All others are CCR with different firmware in them for GMRs, Ham or other services. And lets face it 90% of the GMRS users are not on this forum and use it on the trails, woods and farms all day every day and dont have issues.
As suggested next time have yourr friend change to a narrowband only channel. Channels 1-7 shoudl be narrow band on all radios already and will work fine on your 275. The last JJ I was on we had 16 jeeps on our trail and 14 of them had midlands. 1 had a motorola T600 and the other user had a CCR. He was the only one who complained all day about communications. Not saying he was the issue but when majority of the users use the same gear and one or 2 dont it can casue issues. Day prior the channel given to us was a channel not in any mobiles. Most of the trail vehicles for that trail had mobiles so the trail guide found another channel.
In the end its all how you need to use the radio. The MTX is an ideal radio for the Jeep or Bronco and trail ridiing. As for antenna and placements as you know on the Jeep they suck. Best placement is a hood lip mount with a decent antenna. I run a 1/4 wave on most of my jeeps and never had issues on the trails. I do have a "pepper" shaker on one of the jeeps but again never issues with the jeeps on the trail. If your looking to talk 50 miles then thats not the best option on the east coast. Roof is the best place for an antenna but fiberglass, or no top doesnt help. I di run a half wave in the summer on my roll bar as I dont run a top all summer. In winter its on a fender mount. Have no experience with the bronco but know alot of guys use a A pillar light mount with decent results.
I sue midland for the KISS method. I use my APX for my radio hobby.