stretched fabric wall systems

Hi folks, I was wondering if anybody had any experience with using, installing, or paying for stretched fabric wall systems. Most of the companies that I see selling them, like Fabri-trak and snaptex, have a tackable or "acoustic" filler behind the fabric. I'm wondering if this is required for the stability of the fabric, or will it seem wall-like without it? I'm wanting to cover up some baffles or diffusors with this in places, but wasn't for sure if it would cave in. Also, if you have tackled such a beast, and using say Gilford fabric that's less than $10 a yard or so, what should one expect to pay on a sq. ft basis in the US? If anybody has any info, it'd be much appreciated. This forum is so helpful, and seems to always provide answers to questions that I can't find anywhere else. Thanks.

hmm, posted this to the wrong forum....oops