I have neither of these so I can't comment much but, for gaming, I would not recommend AD-700 lol.
I mean, yes, I know in terms of sound quality, AD-700 for sure is going to beat G930 like nothing.
But when it comes to gaming, it is not necessary that a superior SQ headphone will be advantageous.
If you ask me, I'd get G930 SOLELY for gaming purpose too, I mean well, it's tuned for gaming.
And well, 7.1/5.1 on a headphone is basically a gimmick, depending on how good they emulate the surrounds.
Sure, an Opened back headphone will have better soundstage than a closed, but it does not emulates the 5.1/7.1.
It's still somewhat helpful in Games though, more helpful than an Audiophile headphone (Not to mentioned the Mic too), at least.
Just like I don't game with my K701/HD800. (It just doesn't feel right, somehow)
Personally , I game for the experience not for a living or for winning competition. Gun shots sounds like wacking plastic bag on all of the gaming headphones i tried on . It's hard to believe a hd 800 or k 701 user can actually jump down to gaming headphones .. btw what is your 5/2 channels dac ?