Let's try that again . . .

I'm looking for suggestions regarding a potential speaker upgrade. I purchased a pair of M22 v2 speakers from Axiom in February 2008 and have used them in a 2.0 system for music (primarily), movies and television ever since. I've often thought about upgrading over the years, but never pulled the trigger, primarily because I love these speakers and have never had any complaints. I was going to add a subwoofer a few years back but ended up wall-mounting the speakers with the Axiom full metal bracket. With the additional bass response that the wall mounting provided, I didn't feel like a sub was necessary.

Since the M22 was semi-retired after the introduction of the M5, I've thought about trading in my M22 v2 for a pair of M22 v4 speakers so I had what I’m assuming is the last ever version of the M22. I'd like to get thoughts from anyone who has had the opportunity to compare the M22 v2 to the v4 in a side-by-side comparison. Do you believe the difference in the v2 and v4 is significant enough to warrant an upgrade? Since I'd prefer not to run a sub and the speakers will be wall mounted, I have thought about the M5s but I don't believe the form factor of that speaker will work in my current setup (namely, the increased depth) and I absolutely love the size of the M22s.

If you have any thoughts or suggestions, please let me know. This might be my standard 5-year "upgraditis" kicking-in and since I still love the sound of my M22 v2 speakers, maybe I should just put the funds to some additional recordings instead. I have also been using a Google chromecast audio for streaming spotify to my stereo receiver, however, since that product has been discontinued I’ve considered purchasing an AxiomAir Transformer. If any one has experience using that device or the AxiomAir app, I’d appreciate your thoughts.

Thanks in advance for any replies.