Actually, Onhwy61, whether my response is incorrect or flawed depends entirely on the perspective or premise of the question being asked and you bring up some good points.
First there's the all important question,
In general, is the vast majority of music information recorded at the live event (regardless of the 5 or 10 most common methodologies employed) sufficiently transferred to the final recording medium?
My answer is yes. Perhaps not for every last recording but certainly for the majority of recordings including oldies, Redbook, on up. Therefore, from where I sit, this is not an issue. So yes, my post above had to do with playback only in this thread.
So I think there are two questions remaining,
1) If 2-channel playback systems in general are accurately capturing and audibly reproducing the vast majority of music info embedded in the recording and thereby produce a relatively natural and believable music presentation, then can a similar quality multi-channel system improve on that presentation?
My answer is probably. But since I presume nobody was at this level, this most likely was not the question asked, unless it were at the time pure hypothetical.
2) If 2-channel playback systems in general are NOT accurately capturing and audibly reproducing the vast majority of music info embedded in the recording and thereby produce a music presentation that is anything but natural and believable, can a multi-channel system of similar quality improve on that presentation so that it's at least a bit more natural and believable than the 2-ch version?
My answer here is generally no.
The multi-channel system may create a more intriguing or more exciting presentation (because it's different) but it has to be just as unnatural and unbelievable as the 2-channel version because the system is still only able to retrieve and process the exact same poor percentage of music info as the 2-ch..
So if a recording engineer sticks a couple of recording mics out in the concert hall lobby for the rear channels, sure you might hear a car horn honk, a toilet flush, or people talking there, but you're still going to only hear 50% of the horn honk, 50% of the the toilet flush, and 50% of the talking. Simply because multi-channel is only dealing with the effects of the deficiencies rather than the cause, therefore multi-channel cannot offer a better recovery system of unprocessed music information embedded in the recording.
In other words, the toxicity of all reproduced sound remains the same, whether it's 2-channel or 563 channels. And this is where my toxic water and multi-shower head analogy came in.
-IMO