If you look at what I wrote, you authored a fairly extensive disagreement to something I never said. However, I think we can safely say we disagree that more channels = better.

The problems of acoustics in 500 seat theater will never be the problems I need to address in my living room, thank god. I sit in a sweet spot. I tune my system for the sweet spot. Sitting elsewhere will not be as great, but easily in the "good enough for the chump that sits at the end of the couch" range. Technically yes, more channels/speakers may expand the sweet spot, and even improve the experience. Not enough for me to throw money at, or for my friends to even distinguish. Having 5 front channels in a 16' square room with one couch would be ridiculous. Return on investment, as I originally opined, diminishes quickly beyond four well configured corners and a sub.

Stereo imaging, and specifically creating the aural illusion that a voice is coming from the space exactly between two speakers, or even left or right of center, is easily demonstrated, extremely effective, and totally widespread in nearly all of music we all buy and listen to for our lifetimes. In the front plane of sound, adding channels is a significantly diminishing return. My bet: In a blind test, switching from stereo to comparably mixed discreet LCR 3 channel, most listeners will not notice. Some may be able to tell a difference but not be able to determine which is which, or even which they prefer. Some may rate the 3 channel experience some fractional improvement, and some prudish audiophile will claim it sounds so horrible their day was ruined. The point is if your are spending $100 per channel and your $200 stereo system sounded "awesome", then your $300 3 channel is only going to sound "possibly noticeably fractionally more awesome". About a $2.00 improvement at a $100 cost.

If it is just a center voice track, or even a full range signal that is in a static position, I don't think down mixing and sending to a discreet center signal to the full range LR speakers would noticeably diminish the listening experience. I concede that for movies or other recordings with discreet channel content that pans across the aural pane through the L,C,R channels, down-mixing could cause audible problems.

Yes, discreet channel recordings should be better on equally discreet playback systems, but I maintain that the listening experience in a common room, from a 4.1 system and discreet recording, would be difficult to distinguish from a comparable 5.1 or 7.1 experience. Even down mixing will fall between "no one can tell" and "sure but who cares".

It's pointless for me to grumble about the decision to create the home theater center channel. It's entrenched, and I'm still glad 5.1 killed surround sound.