Chess, I am not the only one that has heard this difference, the M60's do 'open up' when the volume moves beyond ~70-75 db. The sound stage becomes wider, Mojo noticed it as have a few others when commenting on the M60's. The M80's do not exhibt this to the same level, at least in the venues I have listened to them in. Mojo and I did as close to a blind session as possible and the differences were very noticeable when A/B tested. I will agree the differences might be less noticeable with a swapping out of the speakers and some time to forget the true sound of each but the M80s with their dual mids have a more forward presentation and this makes them seem more detailed.
But as you said this is only MY opinion others may not come to the same conclusion just like those listening tests done at Axiom, some still prefered the B&W.
