As the guy from previous page stated, I'd rather buy a good pair of headphones for music and another USB mic, since they'd be better. If you're looking for isolation, closed-back are the ones you want, you might want to find the one that offers great soundstaging, since you're going to use them in competitive FPS gaming.
Personally, I don't have much experience with audiophile headphones (in fact I only have one and tried only few, I only do a lot of reading), but I have lots of experience in headsets. They tend to break a lot, and they don't sound really good too. I like to play games at high volume and these gaming headsets made my eardrums almost bleed (no kidding, they sound horrible). My uncle owned few pairs of gaming headsets from Sony, Razer, etc., and they are all bad in terms of sound quality and sustainability. They're broken after a few months, with mics not working, drivers stop working, etc.
Headphones that have mics (aka headsets) tend to break a lot easier, if not physically, it's the mic or the speakers that breaks. But from what I've read, people always recommend the Sennheiser PC 360 for gaming, and I'm pretty sure it covers all your need. Mic + Isolation (since it's closed-back). I don't know how deep the earcups are, but why do you need to stuff in your IEM when you're using a headphones? Durability and sustainability? I believe Sennheiser do a great job on this part (else they won't survive in the audiophile industry).
Wait, now you're going from headphones to IEM. You're confusing as hell.
And you don't even tell how much you budget are. 50USD? 100USD? 50 Euros? 50 Pounds?
And I really recommend you reading this thread: http://www.head-fi.org/t/534479/mad-lust-envys-headphone-gaming-guide-updated-11-12-12-sennheiser-hd650-added
Some have mentioned it before, but it seems like you don't bother giving it a proper read?
EDIT: This might be a good read too: http://www.head-fi.org/t/582062/need-serious-advice-setup-needed-for-bf3-gaming-music-listeningEdited by acrox999 - 12/10/12 at 1:28am