At least a 600....
Hey Bro...I snowmobile alot, have since I was a kid...I would say that we are past who has the best sled, since they have all come so far...THey are all pretty damn good, and none of them are really low maint...So I would say stay at or around 600cc at least...And I think in the years that you mentioned...Polaris RMK 700 would be a good choice, also the SkiDoo Summits are a damn nice machine...I have the Arctic Cat Powder Special 600 and like it pretty well, it has treated me right for a long time with minimal maint. but I ride the sh!t out of it I don't beat the SH!t out of it...Anyway, all of these sleds are pretty damn good ones, I personally would stay away from the Yamaha in those years, but then again, you could have good luck with them as well...I think that they have a great machine today, but back then I think they were a bit behind...
Cheers