Well, down here in big snow country, south central Wi, I trail ride my 07 RMK 155"x2.4" whenever there is enough snow to do it. The last two winters have been great. Now, will I take it out with only 6" and with no base on the trail yet? No I won't, but get a good base established, and I will ride. I think on one ride last year my brother and I put on 150 or so miles that day. I drop the scratchers and go. My sled has over 5200 miles on it, and I have two lugs missing on the track.
Scottd made some very good points, obviously I did not buy my RMK to ride trails with, but I have, and will continue to do so down here, when there is enough snow that is. LOL.