Pale Rider,
Yes, I have heard of ambiophonics but haven't given it much thought given the constraints on speaker placement. Thanks for the link. I am going to read through it today as I took a day off from work.
I still think that most rooms need EQ if not treated. However, I am beginning to think that maybe Room EQ is not as necessary with the ERRs or Walsh Ohms as it might be with more traditional forward-firing speakers.
Like a lot of people, I am constrained by budget so I am unable to get both a Marantz AV7005 and the Zen Ultra to try side-by-side, and room aesthetic requirements (room treatments are going to be minimal except for traditional room furnishings).
I asked a question over on Audiogon about whether Ohm users found using modern Room EQ beneficial. As might be expected, some said yes and some said no or they hadn't tried it. Maybe in bass management, it might be the most helpful? If that might be the case, then there are analog routes to go such as the Outlaw ICBM-2 and getting the Marantz becomes less of a priority. Dunno.
Since you bring up ambiophonics, Pale Rider, one thing that has long interested me is the Bongiorno Trinaural Processor. It has been described as a pure analog 3.1 version of Meridian’s Ambisonic DSP. I’ve not heard either.
From the Owner's Manual: "...it is a 3-ch L/C/R processor which uses cross-canceling in the L/R channels in order to reduce the amount of C signal in the L/R speakers. This is another way of saying the L speaker has L-xR and the R speaker has R-xL, where x is some scale factor. If x=1, the you have passive surround in L/R, but the speakers are opposite phase."
It is over my head a bit but it appears that the center channel is not a simple summed mono and that all three front main channels are processed via the designer's proprietary algebraic formula. What has heretofore steered me clear of this processor is that Bongiorno states your best speaker must be the center channel.
With matched pairs of ERRs, that might not be a problem, at least for music. Three (L CTR, RT) with the SST Trinaural Processor may be a big improvement over 2 CH, but deriving four or five (movies, multi-channel) out of two is probably too much to ask.
For someone like me who is interested in multi-channel music, the availability today of discreet channel formats is likely the better route to go; for someone interested in staying in the analog domain, the Trinaural Processor or Meridian's Trifield processor might make one re-think "Stereo" only.
So much equipment, so little time (and money).

While you might not be interested, per se, I thought I would return the favor, in Spades, I guess, since it is a fair amount of reading I am giving you but if anyone else is interested, the links below are a good follow-up to the link you provided above.
Some links:
http://www.ampzilla2000.com/trinaural.htmlhttp://www.ampzilla2000.com/trinaural_manual.htmlhttp://www.ampzilla2000.com/trinaural_manual.htmlhttp://www.ampzilla2000.com/sedonaskysoundreview2.htmlhttp://www.audiocircle.com/index.php?topic=67462.0http://www.stereophile.com/musicintheround/304round/index.htmlhttp://www.stereophile.com/musicintheround/904music/index.htmlhttp://forum.audiogon.com/cgi-bin/fr.pl?rprea&1144721220&read&keyw&zztrinaur...http://forum.audiogon.com/cgi-bin/fr.pl?bhome&1076773766&openfrom&1&...