I had the same consideration with mine. The way I look at it, the drywall is attached to the stand. If I move, I can take the tank and stand with me, and I'll have to re-2x4 the hole left by the stand and tank removal, and slap a new piece of drywall up over that. However, if I moved and decided to take the tank with me, I'd have to re-2x4 the hole anyhow where the tank was, so it's not really any more work. Speaking as someone with a slight modicum of authority in the topic of "things that will slow down a tank build", in the grand scheme of things some 2x4's and a piece of drywall are among the least of your worries.
If I was in your position, I'd make the tank glass flush with the wall. It looks WAY better this way (like Steve said it should be like a picture). :mrgreenn: