IMO there is simply no point in rehashing the same old arguments. Might as well argue religion and politics while we're at it. There are excellent reasons for testing a single speaker if you want to discern its character but those reasons are lost on those convinced it takes two to tango and nothing is to be gained from isolating the speaker. I suppose testing a pair is no good for HT; you must test 5, or 7, or 11, or 16, or whatever for it to be valid. And of course we need to be using audiophile electronics...
I think a combination of mono and stereo testing is a good thing; the mono tests should reveal exactly what the speaker sounds like, and dispersion/off-axis measurements should indicate the sound of a pair. But, listening to a pair is probably the only way a listener is going to really understand the imaging and soundstage; getting it off the graphs is tough for most of us, and hearing is believing.
: Salon 2 list is $22k; Studio 2 list is $16k.
Magnepan 3.7 ($6k) and 20.7 ($14k) were on my short list to replace my old IIIa's, along with Sanders ESLs and a few others. I had pretty much ruled out the 20.7's as they were simply too big to be a good fit in my modest room. I have heard many MLs, and the latest models are very good, but if I went ESL I was going to give Roger a try (knew him ages ago and now he lives not far from me since his move from GA to CO). I decided to switch back to conventional after decades with panels "just because". I do not have the years Scott has, but have just about as much exposure to planars, mainly due to working for several high-end dealers for nearly ten years some time ago. ML Monolith, ServoStatik, KLH-9, Acoustat, Beveridge, Quad, SoundLabs, Janzen, Apogee, Carver, Magnepan, etc. Plus many conventional designs. My last "high-end" conventional speakers were IRS 2's though I have Kef and newer Infinity speakers around the house now. Up until this spring I had been running primarily Maggies of some flavor in my main system for ~30 years.
I'm impressed with the sound of the Salon 2's and haven't been tempted to swap the Maggies back in (my biggest concern was I'd be wanting to swap back after a week or two). They strike me as the combination of a lot of things done right and compare favorable to even more expensive designs (though I have done little comparative listening -- no real desire). They are different than my Maggies, but in many ways far less so than I expected. The clean sound and fairly expansive soundstage are there, though of course not the floor to ceiling sound of the big panels. But, I am usually sitting, and the Salon 2's are tall enough to provide a very similar immersive experience. I prefer the Voice 2 over the Magnepan center, but despite the arguably better sound and definitely deeper bass of the F206 surrounds and rears, I need to get them a little higher to better match the immersive experience of the stand-mounted Magnepan MC-1's I was using before, at least in the rear (tall couch back).
FWIWFM - Don