What about them is uncomfortable? The M-80s were incredibly comfortable for me, I'd assume similar for these ones (Though I hate how the M-80s sound).

They have VERY shallow cups... So your ears are inside the pads but resting on the speaker cloth, this is ok for about 30 mins but then gets very uncomfortable, in the M-100 thread you can see people trying to mod the pads, this works for the comfort but unfortunately messes the bass up. People say "they are ok for me but I have to take them off after an hour" to me this is no use..