If raced by a pro then the bike has most likely been abused more in a single season than most of us could do in three years. Other than that it looks like a very nice bike as long as you are looking for a race bike. It isn't intended to be a trail bike. I don't even care much for Trek's but that bike is sweet.
The one thing I would ask the seller would be if he would have any problem sending it in for warranty for you if something would go wrong sometime down the road.
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I may be fat but I'm slow enough to make up for it.