Well Oleg, I'm probably the least experience wheeler around here, but I can say that the larger tires make a big difference. Mountain bikes with 29" wheels/tires are starting to become the new "thing" (as opposed to the regular old 26" tires). I might not have busted some teeth a few months ago if I'd had 29s. <img src="/forums/images/graemlins/notooth.gif" alt="" />
Of course, locked diffs and a lower crawl ratio would help, too. All those little things contribute in a big way.