Though I cannot speak from personal experience, it is generally accepted around here that the M2s, M22s, M60s, and M80s are tonally similar, while the M3s, M40s, and M50s, are tonally similar, but different from the other series.
Again, though I can't speak from experience, and while I accept there is a difference between the two lines of speakers, I would suspect this difference is subtle.
The question you need to answer is "how does your current setup sound to you," rather than your "very serious stereophile friend." If you're happy, don't let his/her judgment cause you to be unhappy with what you have. It's up to you.
If you decide you're dissatisfied, and you're still within the 30 day trial period, you can return the 22s for the M3s, or two more M40s. If you aren't within that return period it wouldn't hurt to give Axiom a call, explain the situation, and ask what can be done. They're very nice folks, and are eager to please. Worst case scenario is you end up right where you are now. No harm, no foul.
