I think I am lucky with my head size. I am not slender man at all, but it doesn't hurt me at all. Of course, 10h a day would definitely hurt me while my HD650s would actually be okay.
I'll make a comparison whenever I can, it will take some weeks though as I don't have access to the HD650s right now. I am nowhere an expert but could give my general impression. I have been too used to the bose QC15 for travelling so the m50 sounded super precise in comparison (the QC15 are awesome but not comparable to studio grade headsets obviously)