Okay a few replies.
I play mostly on the 360.
My Mixamp is old gen, and doesn't do voice chat for the PS3. I really only play first party or exclusives on the PS3.
Black Op's audio isn't nearly as good as CoD4 and MW2 (though I'm speaking in terms of directionality and audio cues....not overall quality, as MW2 has a pretty muddy SQ as a whole). And yes, I run Ninja Pro 99.99% of the time.
I plan on going a little more in depth with the good headphones, including their overall sound signature (warm/smooth, bright/aggressive, etc). This will happen sometime later, and I will let you guys know when it is done.
Like I mentioned before, to anyone wanting to try any pair of headphones for gaming, a good place to start is with headphones that have a good sized soundstage, and a more balanced sound. If the headphones are too colored, it just won't work well with online gaming. This is why I suggest having two pairs of headphones, one for online gaming, one for when you're enjoying a campaign, or just messing about. That is, unless you get something like the DT990 which pulls off both very well (however, remember the sizzling treble that may bother you).
Closed headphones CAN work well. My suspicions on certain headphones I haven't used that would probably be phenomenal for gaming:
D2000 (fun)
D5000 (fun)
Ultrasones with S-Logic on (fun)
K271 MKII (competitive)
Open:
Sony MDR-F1 (competitive)
HD800 (competitive)
K601 (competitive)
Beyer T1 (fun and competitive)
I distinctly remember people saying the HD600 and HD650 didn't have a very large soundstage in DH mode, so it wasn't as impressive. I can't be for certain.
Also have to note, that warm/smooth headphones are usually claustrophobic is DH mode, so they don't work well.
The brighter it is, the bigger the soundstage seems to be able to project further. Just my impressions.