batmanfan,
Thanks for posting that info form Gary Dayton. That makes some sense of why I hear the 3.7s as a bit more open and detailed vs the 2.7.
The 3.7 also floats instruments better around the speakers when they are panned harder left or right, whereas they tend to come more from the speaker on the 2.7, so I get a bit more of a "U" shaped soundstage from the 2.7s vs the 3.7s.
I had wondered if the 2.7s used aluminum for the baffle and now I know it does not.
The Magico A3s speakers I recently auditioned also seemed to disappear better and float instruments nearby the speaker locations, and their cabinets are made of inert metal, so that makes some sense.