I have an 08 and the diamond drive went out right around 1,000 miles, which I guess is farily common. Luckily it was still under warranty (I had one day left!), otherwise dealer said would have been about a grand to fix.
I love the sled...good horsepower, easy to handle. The 10's have what, a different track which I hear is nice, telescopic steering, and more horsepower, and of course hp sells!...BUT...i'm always leary when changes are made to the engine.
Is the 08 brand new? And if so, how much?
For $3500 I would almost say go with the 08 as you will be happy with it. But if you aren't really on a budget, hell, go with the 10. Obviously you are buying at the peak so will be paying a premium for the 10.
Then again...it's all how you want to spend your money!
Let us know what you did and why.