How come Jason didn't get sent to his room?
Mike, I'm totally with you philosophically on this deal. I think many people too easily accept the notion of simply not using the extended bass capabilities of full-range speakers.
If your amp has adequate headroom, I see no reason why the 40-80Hz bass from a subwoofer would somehow be "better" than the 40-80Hz bass from your M80's.
The same principle applies even in my weird room with the M60's. I have tried running them "small", but much prefer the response running them full range with the appropriately REW/BFD-tuned sub.