I've done a ton of headphone gaming lately using an Astro Mixamp or CMSS-3D on my X-Fi card. I've not used an AD700 in this setup. But based on reviews, specs, and graphs, I believe it when people say they are light on low bass. I noticed that with some music.
I had the Denon AH-D2000. They're excellent headphones. They're luxuriously comfortable. Their bass is potent, very much like a good subwoofer, and they can honestly hit below 30Hz with decent volume and surprisingly low distortion. Highs are smooth. Mids are smooth, but a little recessed. I'd rule them out because of their potent bass and because while closed, they still leak a fair amount of sound.
I replaced my Denons with the Ultrasone HFI-680. I like them very much and they're my go-to closed headphones. They're a tighter fit than the Denons, but that also seals them up better, so they don't leak much sound. To my ears and measurements, their frequency response is very even across the entire range, probably the flattest headphones I own. Their mids aren't recessed and their highs are detailed without being harsh. This flatness also means the bass is not subdued. They don't extend quite as low as the Denons, but they get close. Soundstage is very good for closed headphones, even in stereo. My one concern is that since they have real, honest bass, there could be some subtle detail masking during heavy gaming moments. I noticed it in Borderlands when standing in the middle of a Transfusion Grenade explosion. Put them on your list though. You can find them for around $200.