Magnepan 20.1 improved midrange planar units?

HP's 2010 Editors' Choice Awards (Absolute Sound March issue) references "...and its improved midrange planar units" in his comments on the 20.1. I know there are changes to the 1.6 model (the new 1.7 with quasi ribbon technology for the super tweeter and lower midrange/bass), but does anybody have information on the current version of the 20.1? Thanks.

Maybe he's referring to the generation before it - was it the 20R? I've not seen Magnepan making changes without indicating it in the model number.