Jeff, if you think that you are simply overtaxing the M2s in order to "fill" your room, replacing them with a larger model, especially the floorstanders, will likely solve the whole problem. Like I said before, I believe that the M2s are simply too small given your room size and listening distance. If I were you, I would jump on to the M60s or even M80s.
With regard to the Maggies, you definitely have to listen to them first -- people either love or hate them, or the planar dipoles in general. As you may realize, I love the Maggie sound, but IMO you really have to aim at least for the MG12s or MG1.6s, which aren't cheap, in order to enjoy the advantage of the Maggies. They are physically big already, and their "effective footprint" is very large because they have to have a generous breathing room behind and on the side. Needless to say, they are much more room- and placement-sensitive speakers than the Axioms -- that is one reason why I myself haven't bought the Maggies yet.
