i never known one to break in anyway, ive seen the damage after someone landing on a corner of a piller, yea it dented looked like a nail gun shot it. but still never cracked and th 06 (silver gu) rode so nice.
i got an 07 gu long, there a bit heavy in my eyes but still takes alot to break it, worse ive done just bent the snail cam bolts but sorted that out easy. and im only just really a beginner so im hit things quite hard alot of the time and ive had it over a year now.
i think there pretty tough bikes, you would have to seriously abuse it to get it to break.