After hearing them and talking with Jim Winey about the technical changes... imo they sound, well, just about like 1.6's. I heard them in the L/C/R demo (very disappointing set up in that it was convoluted in attempting to assess the 1.7 sound). Yet, attempting to hear past the center speaker and sub, there was nothing "new" about the sound other than seeming a bit tighter, more coherent.
The changes are worth about the $100 Magnepan is charging. This was a face lift to an aging speaker which will likely keep it from falling from popularity. I did not expect it to be a sea change in performance, and it wasn't. No one should think that they might abandon 3.6's or other "biggie" speakers they enjoy for it. Magneplanar is just keeping it a fresh product, but it certainly has not been transformed.
As to its absolute performance, it's just about the same as the 1.6; not going to take away any awards from the big boys, but among the best speakers offered in its price class.