I used this in our Living room while we were in Houston. It had the
worst slap echo I've ever heard. One rug on each side did a great job.
The upside is that a good looking rug is a decorative element. You
don't have to scheme to camouflage the treatment while not compromising its effectiveness.

I suspect that you might get a little more attenuation due to the
kinetic effect of pressure waves moving the rug, however slightly,
at the lower frequncies. Just a hunch.

Skip