I haven't heard the M50X, but have heard the M50 - not sure how comparable, but if my choices were M50 or Kraken FE, I'd take the Kraken FE 8 days a week. I will say, honestly, the FE build quality was beyond anything I expected at their MSRP ($299 at launch), and assuming they haven't cut a ton of corners to get the price to where it is now (e.g. we're just assuming its free market movement) they're silly good for that price. Sound quality wise they will do better with games and movies than with music, which seems to be their design - they're comfortable, offer some isolation, look nice, and have a very bass-driven presentation that works very well with games and movies, but with some music can be a bit much (you can always EQ down or maybe you like a lot of bass). Honestly I think if Razer had just tweaked the voicing a slight bit (e.g. more towards the v-curve than the darker presentation they have) they'dve had a real winner on their hands, HOWEVER, that darker presentation is probably deliberate as it leads to a much more forgiving presentation, which again plays nicer with videogames that may not have the best sound quality (random example: you don't notice the compression ringing nearly at all in Skyrim, where a more v-curve headphone (like Audio-Technica W1000X) it stands out pretty glaringly in some places).
Something else to consider: Creative Aurvana Live. They're about $50 these days, they're comfortable, and they're fairly balanced in sound (at least as I remember it - its been a few years).
I know you mentioned portability, but I'll also throw out there Grados as a comfy option for long-term gaming sessions (I think my personal record is something like 13 hours), but I know some people find Grados uncomfortable, and they (of course) provide zero isolation. Just food for thought more than anything else.
![color]](http://m.bestofmedia.com/sfp/images/design/usr/smilies/smile.gif[color=rgb(7, 15, 20)][/color])
