I think that they will work in the magical 16:9 window that is often referenced over at AVS. My concern is that if the material is too thick (I wonder if something could be created like you mention with the speaker grill material could be done and look nice) that you can get sound waves bouncing around between the false screen wall and the real wall behind the speakers (even with acoustical treatment of the whole wall).
I also really don't want to do anything about wide speakers. I've invested so much in equipment (including more speakers, new projector, new receiver) that I can't see going that route financially or within the plan of what I've already wired up, etc... If I could keep the whole front acoustically transparent, then I can place the speakers beside the screen (like people would do if they didn't have an AT screen) for the wider front sound stage.
