alot of people rag on the 09 as it has a heavier crank. sure the lighter crank will rev faster but the 09's seem to be torque monsters..
I'll second that. I went from an '04 600 Mountain Cat to an '09 M8 Sno Pro, and the very first thing I noticed wast that the '09 makes AWESOME torque. It doesn't rev out and "sing" like my 600 did, but it pulls HARD at just about any engine speed. I was initially worried about it not hitting RPM's when I climb, but I've come to believe that's part of why it's nearly bulletproof.
I just had the shocks rebuilt/re-valved by Andy at Gas Shock Repair. He valved them to 2011 specs, which I'm told is going to rock.
Engine reverse is also awesome, and if you're over 40, it's not just for parking lots. I use it all the time on and off the trail, as well as on and off the truck.