I have an XE RSM and to be completely honest, overall, I like it. MTS2000des has more experience in the public safety industry than I do, I just use it for personal use. But I want to chip in my 2 cents anyway.
I have a Gen 3 XE and I use it with both an APX and an XPR. When I first got the mic, it locked up every now and then and would require me to turn the radio off and on. Whenever I keyed up it kept unkeying and rekeying as I was holding the button. Both of these issues seemed to fix themselves as time went on and I am glad to say I haven't had either issue in months.
EDIT: I just remembered that the mic would also get stuck with the volume rocker. It would only go up 1 volume level and down 1 volume level and get stuck there until I did a reset. No matter how many times I pressed up it would stay at that one level. Again, haven't experienced this in months.
The LED on it is ok. Just ok. It won't light up your house and maybe it will function as a work light or if you drop your keys or something but it certainly isn't too bad. To be fair it's being powered by a radio and it's a flashlight on a mic so I can't say I expected much to begin with.
Audio quality is very good. Speaker gets loud and the dual mics work great in a high noise environment. I used the XE mic for a county fair with generators, music, fireworks, overall loud ambiance and I could be heard clearly every time (Just make sure to talk into the front of the mic and not off to the side).
I personally love the layout of the mic. Two programmable buttons is enough for me and the volume rocker is in a good spot. Works very well with gloves(as advertised) and it has a firm click to it. I always keep the top as mandown so I am left with 1 button that I use for scan/nuisance delete.