VCAs will introduce their own coloration too.
I find it hard to believe that traveling through that many active stages does not result in some coloration. But this is not some unmeasurable voodoo. Errors should show up in common measurements. Phase shift at 20kHz might be a marker for cumulative loop gain error, but overall LPF response would have to be reversed out of the simple phase shift.
A 2 or 3 tone IMD test based in top octave might reveal a little more about overall linearity.
While I am also generally dismissive about hot rodding consoles with new improved opamps et al, in this case it might make a difference.
It would surely be noticeable in your wallet.
JR