I just got a pair of Cobra PR3500DX handhelds. 10 mile range, voice activated hands free mode, 22 channels. My buddy has a pair of Motorola's with the same range IIRC and we tried them out on a somewhat recent trip. They're great on the trail for what we use em for the most...bs'ing back and forth, spotting etc etc. There were many times we were as far as mile apart and had no troubles with the radios, and this was in very mountainous terrain.
Personally I prefer these to the traditional mounted CB, mostly because around here any trail worth wheeling just rips the antenna's off the truck anyways.
They're compact and easy to use so we also use them for events that we go to. My daughter can take one with her and she can go off with her friends for a while...then we can easily find her again.
Rene