Thanks, Prof.
I don't have these yet. Just looking at various ones on the web.
They are various sizes but the one I am looking at to go in back of the couch is 88"w x 53"h. Plenty of room to hide panels under.
http://www.bellacor.com/productdetail/275604.htm
Other ones are long and skinny (26w x 53h) and could go at reflection points.
I don't expect that the weave will be open but if the material was thin enough, would it still allow sound to reach the panels. My assumption (probably wrong) is that if the material isn't thick enough to lend much soundproofing on its own (and would pass through most of the sound to the plaster walls), then it would be possible to add panels to trap or disperse the sound.