Hey there,
I have them... I spent ages researching and trying to decide on a headset never owned one before, and saw the beyer mmx2 as something a bit more decent than the cheaper stuff, or creative models. Both in headphone audio quality and mic broadcast quality.
I am used to wearing the audio technica ath m50 headphones for a long time so it severely effected my opinion on wearing the mmx2 ( the mmx2 is based off the beyer dt231/dt235 btw, just with a mic ). Initially I was quite impressed with the sound quality, but lacking in bass impact and quite harsh on the treble at times, having been used to the more deeper reach and impact of bass from the m50s and more balanced sound overall.
The stereo field also sounded odd to my ears. Small, close and lacking in sense of space. To me it sounded like it veered too much to the right, but that might just be me, seemed to annoy me greatly at first lol
The mmx2 are a high quality headphone still and I think just take time to get used to for me, the velour earpads are soft and comfy to wear but i found after very long periods (after hours) my ears began to hurt, the lobes at the edges. Being too used to the full size pads of the m50s.
I haven't used my mmx2 for a while, neglected lol - but I've not needed them for gaming because of my graphics card problem for some time. I need to give them another good try very soon.
I guess this feedback doesn't sound very convincing, more like you need to give them a try - if you can find them anywhere in a store that is to try, might be very hard!
They will probably suit gaming fine, with a hq mic, just not for stupidly long hours as the pads might cause discomfort for some.