"Just the 26" wheel on Montague is bigger than a folded Brompton. "....
True, ....but not by much. One thing to compare here is weight. My Montague is the XO model (now the X90), and it feels lighter than my brompton (not sure what the exact specs are on the brompton, but it feels very heavy for a small bike), and anywhere that is common place to store a bicycle, even though the Montague does not fold quite as small as the brompton, I can put either bike without problems. (EX: Closet, car trunk, garage, living room corner).
I like both bikes, but everytime I go for a ride, it seems I always grab the Montague. And every thread I read about folders, Montague isn't mentioned as much as some of the others....but it should be IMO. It really is a great bike.