I had MG1s for well over 20 years. And thru a factory rebuild.
If you get them cheap enough and are willing and ABLE to do some DIY, there is no reason they can't serve you well.
Furthermore, even though they are not the most sensitive speaker, they can be made to work with 100/side or less.
Between the original model and the final there were 'a' / 'b' and 'c' revisions. I think they were crossover and cosmetic mods.
White Bear probably no longer supports this speaker. CALL them, since they don't do internet. Also, MUG (Magnepan Users Group) should be on your short list of bookmarks.