I have the XD material (in fact, I bought a fixed frame... considered DIY but opted for the Seymour screen (very glad I did - it's awesome)). I've been very pleased. I've had a few people to view it and the weave is excellent. Very transparent audio but has no issue with the video. Nice bright image. Not much can be done though if cost is an issue...
I'd be hesitant to put anything behind a non-transparent material. It might work, but I think you'd lose some of the clarity and punch. I'd really work to make it AT if possible.
Not sure what the Infinity speakers cost... but I'd seriously consider some of the internet only manufacturers. The bang for the buck is huge... and most offer 30 day policies. I opted for Emotiva and have been extremely (understatement) pleased - but I bet you'd get the same (outstanding performance with lower costs) with any of them (Axiom, SVS, HSU). You can't see them in person before you buy... but that is the only negative. You might be able to ask in one of their forums if there are any local owners so you can see it... I know I've demo'd mine already for interested buyers

(and they both bought!)
< edit: just checked pricing on the infinity speakers... if they are good - that's a steal ($200 a pair!). Infinity used to have a good name but I haven't checked out any of their current stuff >