I ran a Timbersled LT on my 2011 300 XC 6 speed for a season.
I would rather have the SX 5 speed for snow, other than the road. Your top speed will be like 35 ish MPH.
6 speed is faster top speed but a little gappy. I wouldn't want a W myself.
E start is nice on the XC.
I did the Pro Circuit pipe, 300 SX CDI box, Shorty muffler, and had Slavens cut the head. Also run the red PV spring with the screw flush. Runs great and added a nice bump in power. About 5 hp on the dyno.
I went back to a sled but if I do another snowbike, I will go back to 4T. I thought my 300 ran pretty inconsistent and you have to run it hard compared to a 450 or 500.
That being said though, if your on your game, it runs with a 450 no problem. Rode with a bunch of them and didn't see much difference (which makes sense since my 09 450R Honda actually made 2 less hp on the dyno than my 300 and most of the 450s are +/- 2 hp of my 300).