@boxcarman: Bruce Thigpen openly expressed his admiration for Jim Winey's invention of his planar-magnetic design. I myself was an early adopter, buying a pair of Tympani T-I in 1973. Thigpen went on to study the Magneplanar, and had an idea for his own version of the planar-magnetic driver.
In the 1980's Thigpen introduced three loudspeaker models: the LFT-3, LFT-4 (of which I have a pair), and the LFT-6, all of which featured the Eminent Technology LFT planar-magnetic driver, which is a push-pull design (the idea Thigpen saw as a way to improve on Winey's design). For years all the Magnepan drivers were single-ended, and the lower cost Maggies continue to be.
Keeping the conductors that are attached to the Mylar diaphragm within the magnetic field of the planar-magnetic design is a means of eliminating the distortion inherent in single-ended designs (in his TAS review, Greene talks about the low-distortion character of the LFT-8b). The more expensive Maggies now have push-pull drivers, the 20.7 and 30.7 for sure, the 3.7i I'm not sure about.
How much this has to do with the sound of the 1.7i I can't say. All I know is that that model sounded---as I said above---"wispy" to me, images lacking body and substance, more like a ghostly apparition than a flesh and blood image. And whatta ya know, Guttenberg characterized the sound of the LRS+ sitting next to the LFT-8b in his living room just that way when comparing the two. I haven't heard the 3.7i, and very much want to. Until I have room for my Tympani T-IVa's, the LFT-8b will just "have to do." ;-)