i don't really blame them, it can happen to any racket. although i watched a lot of Zhang Nan play with it and Zhao Yunlei with n50-iii, and they broke several rackets in the clashes.
N55-iii is great for singles, but i wouldn't play doubles with it.
I'm getting my n50-iii this week and i will only play singles with it, i have jjs for doubles (although it already has a crack too, dunno how it happened, never clashed it).
Now I am gonna choose between MX JJS and MX 90.
The MX 90 thread said it's faster than JJS. Yes I am looking for that but I fancied JJS because of the beautiful paint job. But I am afraid it's too stiff for me.
Normally I strung my racket at 28x30lb with NBG99.