...sounds like a bunch of nick picking... Looked at an 07 recently. Didn't know about possible cracks. Am still considering an 07 to 09. Prefer riding over wrenching. Last thing i want to do during our short riding season is to be stripping down the bike to the frame and fixing a minor crack. Lost enough riding time last year redoing a ktm engine, waiting for parts, head work, etc. After looking at several 450 engine internals, considering a yz450f as next purchase. Riding terrain, riding style, seat time, and rider weight are likely significant contributing factors. My 220 lbs plus gear may cause a little more stress on landing than most other riders.