First and formost change in the new 850 that I noticed was the thumb to track connectivity. The 850 really does have a rapid response to throttle position and can be noticed easily. The condition I rode in where 3-4' of fresh powder headlight deep. The handling of the the gen4 was hard to judge because the snow was so deep but i did find a south facing slope that had a more set up snow and wasn't as deep to do a few passes on. Sidehilling on both the left and right side seemed equal in effort and could easily move up and down the angle of the hill with little effort and the sled seemed to want to stay on its side better than the xm that tends to want to fall back on both skis sometimes when you start slowing down or speeding up they tend to want to climb. I cant really speak for the power as I ride a SHR 880, so power of the 850 was not as good, but the stock sled guys I ride with all mentioned they where impressed with the power. One of the guys rode it on the trail and said you can really wheelie with it and had alot of fun mashing it through the whoops. The seat is small and looking down at your feet it sems the boards are wider but in reality the illusion comes from your ability to plant your feet in the running board without bowing your legs out. Very comfortable feeling having a good stance in the running board rather than on the rail edge. Also you can really get forward on this machine which really made it shine in the deep you could move back to a more forwad stance while WOT across the meadow and the sled would pick up some speed and this was also noticed while climbing. Over all the sled is a winner with the clutch, light weight crank and lighter track the throttle response was excellent. The comfort of the handling is 100% better with the taper tunnel more forward steering and running board. The tunnel on seemed to hold a bit of snow on each side from the running board support on the back to the bumper, not very much at all. I have my snow check ordered and plan on a mesh hood with a can to shave some weight.