My advise is to take a "staggered" approach. For example, you can first order just a pair of the M22 alone and try them as the front L/R in your existing setup. The 4-week trial will tell you plenty about how the Axioms sound in general. Even if you decided that you do not like them, the return shipping would be modest just for the M22's.
I also second that once you upgrade your main speakers to a high-performance set such as the Axioms, you will sooner or later want to upgrade the sub as well. A good sub makes a huge difference not only in the bass but in the entire soundstage. I recommend the Hsu subs, too.
But these upgrades do not have to happen at once. In fact, my experience tells that it is more "fun" to upgrade your components one by one over a certain period, so that each time you can appreciate the improvements brought by a new piece of equipment.
