Originally Posted by rabident
With heights, wides, and multiple surrounds spread around a large enough room, does it change the acoustic importance of using an AT screen?
I'll echo jlanzy's comments, since I agree with his reply to you, plus add a couple of points:
First, room size doesn't matter when it comes to number of speakers as much as seating location does. For example: you could be in a huge room, but if your seating is at or near the back wall then you're a poor candidate for a 7.1 set-up (no space behind you for the rear speakers). By comparison, my first 7.1 set-up was in a small 11' x 13.5' spare bedroom. My futon was 8 feet from the front wall with the side speakers in-line with the seating, which put me at least 5 feet away from the rear speakers on the back wall, and provided excellent rear-vs-side separation in the surround field. So don't worry about having a "large enough" room, as long as your seating is away from the back wall.
Second, as jlanzy already mentioned, having an AT screen has no bearing on the number of surrounds, wides and heights. However, one thing you can do to take advantage of an AT screen is put lots of thick absorbtion behind the screen. Even in this day and age of surround sound, the front soundstage remains critical; that's where your attention will be focused, whether watching a movie or listening to music. With your brain working to create phantom imaging between your front speakers, the last thing you need is reflections from that direction interfering with process and muddying up the soundstage. Absorbing reflections from your side, rear and wide speakers that are bouncing off your front wall can make it easier to hear the direct sound from your front speakers. Worth considering if you plan on using an AT screen.
BTW, how far are you planning on sitting from the screen?