Usually you are kind of useful, but in this thread you are kind of just being difficult. You didn't answer my question about what comparisons YOU have done, not what others have done. I've done my own comparisons and come to my own conclusion. The EXACT reasons that you give for diffused sound are what I don't like about multipolar surrounds. The directionality is what makes it work.
Yes, for movies there are things that are going on back there that are supposed to be diffused sounding, and they ARE. For music, when they place an instrument in a particular speaker, that is where it should sound like it is coming from, not EVERYWHERE behind you. When things pan around the room, as man multichannel audio discs do, I want it to actually sound like it is moving around, not just blending in behind me. Audio discs off the top of my head that do this: Roxy Music's Avalon SACD, Steve Miller Band's Fly Like an Eagle, Pink Floyd's DSotM SACD. All have slow pans from speaker to speaker or audio that intentionally uses all speakers at the same time. On Avalon, the soundstage is broken up with the supporting singers in the rear and it works surprisingly well. Every Porcupine Tree DVD-A has sounds in specific speakers. Eagles Hell Freezes Over - Seven Bridges Road has one voice in each speaker and it sounds amazing. Do you think they intended that track to be listened to with the two voices in the surrounds diffused? For movies, when a bullet flies from the back of the room to the front or vice versa, should it go from "somewhere" to sounding crystal clear? Not all sound in the surrounds is supposed to be diffused. I agree to disagree...
AFAIK, when m/c tracks are engineered, they are engineered on monopoles in a treated room, not bi/dipoles.