I have one. Bought it some years ago. I've tried it in a couple different rooms, with different placements within each room. It appears to work better positioned higher off the floor and in closer proximity to the listener. I ultimately found that I did not like the effect- which seemed to homogenize the sound and take off some of the raw, more visceral aspects of sound reproduction. Other people at the time (it's been a while) never noticed any difference when I would switch it in and out. I'm not sure it is entirely psychological, I actually felt somewhat nauseous when I ran it the first few times. I think it does something, but I can't explain it and wouldn't try to--
I still have it, mounted on a stand at height in proximity to center chair listening position. But have not turned it on in quite a while. Is it even made any more?
(PS: I know all the above sounds like crazy "snake oil" and I'm not usually a buyer of such things but I wanted to try it after reading some positives about it).