I would also say say that as far as durability goes, the m50's seem more sturdy than the 750dj's
And the Shure's do also creek when u open and adjust them because of their plastic contruction, but it has never bothered me, it doesn't happen when they are just sitting on ur head
The shure's don't extend extremely far so if you have a really big head they may not be for you, the m50's fit a very large head better.
Overall comfort, ATH M50's are more comfortable than the Shure SRH750DJ's, they both clamp tight at first, but long listening is pretty comfortable on both






