This is a difficult discussion, it harks back to 2 years of thought crimes I did back in 2008, so I might be a bit fuzzy and my brain is frazzled!
Looking at most SQ systems and indeed the patent on Shadow Vector (all power to it - keep it up guys!!) The VGA's are applied at the outputs, this directly means you need to be very careful how the VGA's are controlled to prevent apparent pumping and image shift. This is true for example if your "logic" implies that the signal is to be "steered" to the rear left then typically you either boost the rear left or attenuate one or some of the others. One of the difficulties of that is if you boost one signal you really must attenuate the others in some manner otherwise you automatically get a "pumping" and a simultaneous image shift.
An advantage of the variomatrix as in QS is that the steering "constants" that are actually variables with the equations automatically do this see saw balancing act of maintaining a constant level output even though a boost is happening on one channel (or a cut).
In regard to multi band, I differ on that to (with the greatest of respect- who knows I could be wrong!!). I spent a great deal of time looking at music under spectrum analyzers and characteristic as far as possible what bands the fundamental and its subsequent harmonics were contained in. To prevent image smear of an instrument - meaning parts of the instrument/ voice being spread between speakers I wanted to keep as many of the harmonics in the same band group. This is to avoid the situation where a dominant primary harmonic of say a midrange instrument shifting some of the upper harmonics of a bass instrument - for example. This causes smear.
Now here is the dilemma, logic says the more bands the better individual control of the steering, but in doing so you enhance the smear. I eventually decided music was best characterised into boom, squawk and twinkle!! You know bass drums, voice/ guitars/ piano's, transient stuff like triangles etc. Many of our users have reviewed how the SM tends to move voices and instruments as a whole without smear- well this is one of the tricks!!!
I have said many times we have resisted a numbers chase but we have always moderated our persuit of big separation numbers in preference to clarity and precision of image without smear or pump as was characterised by many of the earlier systems.