I never have understood the appeal of the Magneplanar speakers. Their literature has a bunch of criticism about boxes and how music doesn't come out of a box; I think it shows the disconnect between the high-end industry and real music. When I play my violin or guitar, the music is coming out of a box, and the boxes I have that say "Fender" and "Marshall" are definitely boxes, and the recording mikes are point sources. Now Mags may sound nice to some people as a "stereo", but not to me when you compare them to real music.I agree with George below- the dynamics make the sound. Speed and detail in the amps to reproduce attack and decay of notes with speakers that can handle that would be next on my list. These cues set up the psycho-acousical illusion that "re-creates" music, and Pi's do it very well.
I also question the concept that a speaker company is selling a speaker at a loss to get people to buy more expensive models- people that have money to buy more expensive models will do so, people that can't afford them won't. After all, they do give mylar away free with potato chips... :)