The difference between 'old' Maggies and 'new' is the difference between pole piece forward and mylar forward.
The old way, IMO was better. My original MG-1s had a character and feel about them not equaled by my 1.6s, until I did a rotate-in-place.
Anyone having 'brightness' or treble problems with Magnepan should try a simple rotate in place test, give 'em a few minutes and adjust to preference. Maybe even give it a day or more.
When I did the rotate thing, the change was so startling that I knew they'd stay that way. Had more of the character of the MG-1 without the heat of the 1.6 as well as a fuller center image and simply a wider 'listenable' seating area.
Cost? just a few minutes and the electricity you were going to use anyway, to listen to that new album.