Magnepan 3.7's versus 20.1's?


Anybody here had the chance to compare the new Magnepan 3.7s with their longtime flagship 20.1 speakers?
salmonsc
My 3.7 s now have a few hundred hours and the bass panel is kicking in with a lot more force and presence.
Ordering 3.7's Monday,trading 1.7's. I have auditioned 20.1's they are great but too large for my listening room and not in my budget. I also heard rumor that the 20.7 will be out shortly.
20.7 is now official:

http://www.avguide.com/blog/first-listen-magnepan-s-new-flagship-207-loudspeaker
Assuming a 'shoe-box' shape, What is the smallest room dimensions in which the 20.1's and 3.7's will work well?