I had some motocomm headsets, and although I bought them for CB radios, I tried them out with a couple of FRS radios once.
They worked about as well for the FRS as they did for the CB. Which was...iffy at best.
The units seemed to work at first, but from the outset, we had trouble with the range, which I blame on the CB. My wife had trouble picking up anything, which I blamed on the placement of the handheld CB and all that Jazz...I had extremely poor transmission range. Performance quickly degraded, by the middle of our first trip, my wife's headset would emit only a high-pitched squeal when she hit the PTT button. We tried swapping CBs, which made no difference.
Then at some point, my headset started acting up, and by the end of our trip, it had quit altogether. When we got home, I tried swapping various components between the headsets (basically each cord and PTT button) to try and isolate the problem, but I came to the conclusion that the same part must be bad on both headsets, probably either the cord that plugs into the CB or the headset unit itself.
All in all, they were a complete waste of money, and I'm extremely glad that I used a 'found' and a borrowed handheld CB instead of spending money on the midland units, because I'll just give the borrowed one back and keep toss the found one in the glove box of the truck.
I look forward to installing the J&M CB on my FJR once the glaciers recede.