I also have been to Goodwins and spent 2 full days there comparing the Altairs to the M6. AT the time, Goodwins did not have their M5 yet. In case you haven't been there, the room that these speakers is in at Godowins is acoustically very, very good. The electronics that I used for most of the audition were the Spectral 4000S cd player, the ARC Ref 3 and the Bolder 2050 mono block amps. The Goodwin's room is large - approx 21 feet wide, 30 feet deep with perhaps 11 or 12 foot ceilings. They bring the speakers well out into the room and are spaced far apart (about 13 feet center to center). The seating position is about 3 feet from the back wall. The M6 that Goodwins has does have the Nanotech midrange and mid bass drivers. In my mind, both speakers are wonderful to listen to and it will come down to personal preference as to which you would want to own. Also keep in mind, that both speakers are exceptionally coherent and dissapear very well. I agree with Koegz to a certain extent that the Altair with its 15" subwoofer had a more powerful bottom end with a better ability to pressurize the large room at Goodwins. But, the M6, to me, had a little more resolute bass than the Altair. Vocals on the Altair are more seductive sounding than with the M6. I felt that with the M6, vocals are also very good, but with a little more texture and slightly less round than with the Altair. But to me, the biggest difference is in the upper frequencies, where the Altair is a more laid back speaker than the M6. If you listen to alot of jazz percussion pieces with cymbals, high hats, etc - you will hear this difference between the speakers immediately. The M6 has a little more life when these instruments are played. It really is a different presentation between the speakers - overall I preferred the sound of the M6's, but make no mistake - one is not better than the other - its which presentation do you prefer. Ultimately, i did get a chance to audition the M5 at a local dealer where I live and I ended up purchasing the M5.