Those little Polks won't match well, but we are only talking about the surrounds. I think that it would be fine until you have the $ for matching surrounds.
Perhaps you should arrange a demo with an Axiom owner to hear the M60s? What kind of music do you listen to? What other speakers have you heard and liked/disliked?
Whatever you decide on, I wouldn't be overly concerned with mating your new speakers to those little satellites - that system will probably be in the bedroom once you experience a full-sized surround system in your own family room.
