All depends on how much you want to spend really. I personally did the '08 for SUBSTANTIALLY less than you can get '09's for. The only real differences on the '09 are engine reverse (saves a few pounds for sure, most of the rest is hype if you ask me as '09 DD's have their problems too), powerclaw track, the rear bumper/tunnel setup, and 2 wheel. If, and only if, you are comparing Sno-Pro's then the '09 also has the telescoping riser. For the price difference I personally got the '08 and added telescoping riser, 2 wheel kit, '09 rear bumper/tunnel mods, '10 seat, and will still be putting on a Powerclaw. Sled for $7k + ~$20 for 2 wheel kit, ~$175 telescoping rise, ~$160 for bumper/tunnel, ~$240 for seat (would do this also to an '09). That puts me at $7600 and Powerclaw will send it to around $8200, or under $8k if you don't count the seat which I would add to an '09 too. I will have everything an '09 does for cheaper than I could get an '09 out of the crate other than the ~6 pounds from the engine reverse. I also geared mine down to 55/65 and will be installing SLP pipe which should have it much closer to a '10 for right at $9k total. I don't mind doing the work and can spread the cost out some. On the hill my '08 with the above stuff will outperform an '09 and should be close to a '10 while still comparing new out of the crate sleds.
Without spending the bucks to go to the light drive on an '08 the only real thing you could do is remove the solenoid and such from the reverse which would save you probably 3-4 pounds. If you EVER use reverse that wouldn't be worth it if you ask me.