The NRC measurements of the M80s (in which the assumption is that the M60s will be relatively similar) can be found
here.
Bobcox is correct in that the Hometheatrehifi review essentially measures a large portion of the reviewer's testing room making his measurements valid to his listening area (within the limitations of his recording equipment used).
All that aside, there is a quick peak in the NRC measurements at the upper end of the spectrum near the 16-19khz mark, but if the reviewer thinks that is the cause of the M80 "brightness" then he is a person who has never actually heard a 20khz tone!
The VAST majority of sound of music and movie material occurs in the midrange spectrum. A peak at the
very upper end would hardly be noticeable to merit the title of 'bright' speaker.
In fact, there is a large dip in the upper frequency range 12-14khz mark, yet no one has called the Axiom M80s 'laid back'.
