I've had one on my KDX for about 400 miles now, its about toasted, probably change after this weekends HS. It worked awesome for about 300 miles, but braking strength has greatly diminished the last 100 miles or so.
Due to some confusion in the Rocky Mountain catalog, I ordered the bigger tire. It was tight but ultimately fit okay. I put the 12T sprocket back on in order to move the tire back, and that created enough clearance that it didn't rip the mud flap off. One benefit of the larger tire is that it seemed to have quite a flywheel effect, seemed to smooth out the power in mud & goop.
If I go back to the MT16 I will go for the 110 as Ben suggested. Depends how much I like the Maxxis IT that goes on next.