The ATHM50x looks badass. What bothers me about it, however, - and what you generally don't find in the lower-tier wireless headphones - is the earpillows, the padded circles around the sound sources. How do they fare? The only ones of this kind I had did not fare well: the pillows just kept pressing against the ears and made them sweat (which I didn't even know ears can do beforehand).
Hmmm. With mine, my ears do sweat when it's hot or when I wear them for several hours at a time. But they're breathable enough to not make them sweat 95% of the time. You might be different, though. I'm reading on Amazon that this newer version has upgraded padding material. I don't know if one could say for sure how comfortable they would be without trying them on for several hours. I will say that these headphones are designed for long periods of use, since they're really designed for studio monitoring. Another caveat that goes along with them being for studio use is that they're very accurate, and some people actually don't like the way that sounds. They don't boost any particular frequency to make the music sound more "dynamic", the music sounds like however it was recorded. And the sound is so much clearer than cheap consumer headphones that you may find unpleasant surprises in music, like if a song is poorly mastered and has some clipping when it gets loud, you can hear it. On the other hand, it makes well-mastered albums sound better than anything I've heard before. For instance, I was never a huge Björk fan before I bought nice headphones, but I am now.
I wouldn't count on it. I noticed that Guitar Center has them in some stores. At least, they have them in stock near where I live. It also looks like their return policy will let you return them after trying them on. Or maybe they'll let you try them on in the store. Maybe you could go there, or if they're not nearby, maybe there is another store that has a return policy that will let you try them on.