Thanks MLE for the great thread. It's an awesome effort and contribution. I've read through it a few times and enjoy your updates / insight.
As to what I can contribute:
I currently have the LCD-2s as my primary headphone, as well as the HD-800s, the Beyer T1s, and the MrSpeakers Mad Dogs.
I have used the LCD-2s, the HD-800s, and the Mad Dogs for online FPS gaming. The games include Planetside 2, BF3, CS Source, etc.
In my experience, with my setup, I have observed the following:
The LCD-2s are not suitable for FPS by any standard. Yes, the explosions sound amazing. The sound is GREAT. However, the sound stage is all over the place. You can hear foot steps in places where NO ONE can be (such as in the ocean). It jumbles it all together and there is no sense of separation in the position of the individual sounds. You will not be able to predict where the opponent is coming from or where that shot was fired from. I had no luck with this on ANY game. That's my experience.
The Mad Dogs seem to do better at positional audio for games - for some odd reason, but are by no means something I would rely on in terms of using audio to determine the location of my enemies.
The HD-800s are like hitting ` then typing audio godmode. These things place the sounds PRECISELY where the opponent is - and they do it on a large scale. You can EASILY locate several opponents all at once at various locations around you. You can position yourself in a building and hear opponents above you, beside you, running outside in multiple directions, etc. and actually count the amount of opponents and judge the direction each opponent is heading. Of course you have to focus your brain on accomplishing that task, but that's not the fault of the head phone. The headphone provides the information and you have to be able to interpret it. Once you learn to process that information the HD-800s are providing you, you have a definite advantage over your opponent. There have been MULTIPLE times in games like BF3 (which I've read doesn't have the best positional audio, but does have GREAT audio quality) where I've been in a close quarter combat situation and been able to stop, listen, determine the location of multiple opponents, and proceed to take each of them out one by one, all the while judging their movements as they hear me killing their allies, and myself being able to adjust to that based simply on the sounds of them moving around me through the walls, hearing their footsteps, their ammo reloads, their shuffling around, etc.
It's awesome. I have the Q701s on order and they should be here this coming Thursday. I'm excited to see how they compare against the HD-800s.
Just wanted to provide my experience, but yeah. If you already have the HD-800s for music then definitely use them for gaming. It's just a HUGE added bonus to these cans.