ive got a gas gas 250 2007, only had it just over a month im really happy with it. found out my exhaust needs repacking last week which i would imagine is the same with all bikes, and like manx2day said, so long as you look after it and keep on top of it then apart from general wear and tear then they are as reliable as any other bike. my mate has just bought an 06 250 which is in very good condition and that is as smooth as anythin.