Just as what the title saids, I'm seriously thinking about getting a 30" ACD and I've already returned my 20" ACD and might sell the 23" ACD.
Yes, I play WoW, and intend to buy CoD4 for mac once it is available.
What specifically are you concerned about?
The computer and graphx card are adequate to play WoW at those resolutions, you won't max out at any time, but very seldom are you ~30fps, maybe in high lag cities. With all settings set to MAX, playing windowed mode I'm typically at 50fps.
Mac Pro 2.8GHz, 10GB Ram, Raptor 150GB, 8800GT