OK, one last observation. The detector seems to be mono-summed, so that instruments that are hard-panned (and therefore not masking the center vocal) are attenuated the same amount that they would have been had they been panned center and actually causing a problem.
This is a big limitation, I think. It would be much more transparent if it were either a true stereo effect or worked in Mid/Side. Ideally, you only want to attenuate sounds that actually mask the reference track.
For me, I've decided to pass on this one for now, but I'll definitely come back to it if there's ever a rev 2.