On the trails about NC/TN there are some I cannot get the Teryx into. There are others where ATV guys say, WOW you got that thing up here!! OMG. I also have an ATV and I have ridden it a few times since I got my Teryx.
In the rocks, tire sidewalls take a beating when I ride ATV trails, but so far no punctures. I carry a spare, and also plug kits and portable 12v air compressor. I just ran into a National Forrest Ranger a week or so ago at Buffalo Mountain Trail #29 in eastern TN, and he told me that they turned in all their ATV's and will be getting
SxS's for paroling in 2009, so the National Forrest trails should be getting wider for us for sure.
Also, in the woods, the low overhangs can also be a problem that ATV's can slide right under. I have had to bushwack through the woods to go around a low overhang twice.