Planar Speakers and Diffusors

I have the Clarisys Speakers. They are the Planar type. I would like to treat the wall behind the speakers. I have been told not use any type of sound absorber, so I am interested in the GIK Acoustics Q7d Diffusor

I have a large 85" TV in between the speakers, so the only area that can be treated is behind the Planers. Check out my systems page.

I have yet to find a review of these diffusors, so has anyone used these and can comment on the effectiveness?

ozzy