Does this affect the tone of the cab?
I was imagining it might act like a big port and make the one more full-bodied... kinda like a oversized cab?
I've tried it, and it worked well - exactly as you described.
I never used the cab at high volume though, so I can't comment on that. Certainly it was as loud as the equivalent 2x12 with two of the same speakers in it. The only negative point that I could say is that I found the detuned cab did not seem as "tight". The overall tone was fuller, but just a bit "sloppy" (in a vintage sort of way).