XM T-motion, only way to go
My last sled was a 05 REV ho 800 with a 151. Bought a 13 XM last spring and put 900 miles on it till it got ghost rode off a mountain in Seeley Lake. Rode the sled out but it was totaled. Once I had my insurance check in hand I bought another 13 XM 163.
Love the sled, handles great, pulls awesome, does not eat belts, sips gas and oil. Ride all day in deep heavy snow and your not tired.
While I was waiting on my insurance check I rode my old REV, OMG how did I ever ride that sled for a full day. Huge difference.
Downhill turnouts are a breeze.
If you get an XM you will hate it for the first half of the day as the balance points on the XM and REV are totally different. But once you get used to it you will never go back.
The biggest problem with them is if you ride in bottomless powder and ride with POO or CATS and you get stuck, you are on your own as they will not be able to make it up the hill to help you out (I have the pictures to prove it).