I currently ride a two stroke YZ250. I rode a 2010 YZ450F on my track a few months back. Considering buying a 2011 model when they become available. How have your 2010 450s been holding up? would the average weekend motocross racer be able to get 2 seasons out of the engine without any problems? Would that be no problem, or would that be pusing it? I realize the 4T takes more attention with things like valve train maintenance and oil changes. I'm ready for that. I just wonder what kind of service life real world guys (not the magazines or service manuals) are getting out of these engines when racing them hard.