I don't find the m80 or m60 bright either. They are amazingly accurate speakers, but I was wondering why this issue keeps coming up with speakers exhibiting flat FR. It's a crtiticism sometimes levelled against any speaker with linear response which I always felt was its most desirable feature. I've heard the same criticism against PSBs, Paradigms and Mackies to name just three other companies. I guess I wasn't the only one wondering because when I picked up the December issue of Home Entertainment magazine last month it featured an article with PSB's Paul Barton doing listening tests at the NRC on this topic.
Interestingly he found that a certain small group of listeners tended to associate linear FR above 5000hz with "brightness" in a speaker. The 5000hz inflection point seemed to be the point above which those listeners preferred a gently declining ("warmer") FR curve even though accuracy of the recording was compromised.
So I think the phenomena is real for a certain minor group of people. The same ones who seem to like "warmer" sound. What I don't understand is why those users exhibiting this sensitivity don't simply lower the upper range response with treble control or equalization in the receiver.
By the way some of the loudest crazies who love to bash Axiom at AVS are retail audio merchants who feel threatened by internet sellers. One of them even goes so far to complain about ringing from aluminum drivers even though he admits to tintinitis in the ear where he hears the ringing.