No, but I filled out their form to assess my room and he replied it's unusable (which I presume he says for any room not up to professional standards based on his many video). Also, I believe his absorbers are a variation on a theme of activated carbon as a key ingredient.
This room doesn't seem like an unusable space. Not sure why you were told that. The room I am building is 17'-0" X 21'-0" with 8.25'-0" ceiling height. I am thinking about building some of the bass management into the walls, and am investigating the carbon technology. Surely I am not the only one that is checking out Dennis's options. Unfortunately, no responses here other than yours. Appreciate your input though.
Dennis said my room is not usable because he expects 2 channel and HT homeowners to knock down walls and have a specially built room like pro studios or cost no object audiophiles (check out his videos). With my sub and DSP I actually get excellent bass in my room so no need for his consulting.
Good luck with your room which is about the size of mine. You should be able to accommodate many speakers with a nice distance to the sweet spot.
newmill i have hired Dennis for a rather involved build which includes literally tons of carbon. Dennis is legit and rather straight to the point. my build is a metal building with dedicated 2 ch room. absorption and diffusion will be in the walls. i would give him a try but its not inexpensive.