Sean, I find your statement interesting, regarding visual clues lowering our responses to audible clues. I find this to be absolutely true as far as listening to our rigs at home is concerned, not so however listening to live music in a hall, where visual contact gives me at least the illusion to pinpoint the source also aurally better. I cannot say, if this is an individual idiosyncracy of mine or if there are established scientific facts, which would prove me right or wrong.
It is true of course, what you state about dipoles. With clever placement however, the out of phase effect of these speakers cannot only be minimised but actually be used to good advantage. This is true especially, if your preferred software are large classical orchestras, recorded in halls with a fair amount of reverb to them. Here you can use the out of phase part of your presentation to a good end in mimiking the effects of the hall, therewith strengthening the psychological impact the music will have on you. It seems more "real" then in your listening environment, although of course actually less real regarding what is found in the actual mix on the mastertape. I've even gone so far in the pursuit of this effect to place a pair of Quad 63s at right angles to the main body of speakers, which I will blend in very carefully in order to get this "out of phase effect" with recordings which I find too dry, lacking natural reverb. In getting this right, there are other prices to pay of course. We all have to settle for that compromise which brings us the most in musical enjoyment.
By the way, we have a cable station here in Zurich, which sends lots of old Jazz in mono and I listen to a fair amount of classical music on mono lps. Compared to stereo, the soundstage is of course less wide, but the placement of instruments or groups of them in space in well recorded presentations, though not as pronounced as in stereo, is certainly there.....
Cheers,