I went back and forth over the Axiom M3, the
Axiom M22 (the next step up the Axiom food chain) and
Usher S-520s and wound up with the Ushers. Not having heard the Axioms all I can do is give my reasons and my observations about the Ushers.
Axiom vs Axiom: Was solved by a call to Axiom. They claimed that the M22 has a flatter frequency response than the M3. I haven't seen the charts but that was their claim.
Centers: That left the M22/VP100 vs the S-520/S-525. I didn't like the fact that the VP100 needs to crossover at 100hz. That's too high for my taste. On the other hand my old receiver didn't support 4ohm speakers and the Usher center is 4ohm.
I got lucky and found a factory authorized dealer on eBay with a single new-in-box S-520 and use that as my center.
Placement: The Axioms are rear ported while the Ushers are front ported. I needed to wall mount the left and center inches from the wall and had concerns about the ports sitting that close to the walls. Adding to that issue the left and right would also be at different distances from the wall. The Ushers being front ported eliminated all of my placement concerns. However most reviews suggest that the Ushers play best without the grills so that could be a WAF problem.
Output: I did have concerns about filling the room. My master bedroom is 12x18 with a cathedral ceiling sloping from 8-14', and my listing position 15' from the speakers. Total cubic footage with halls etc is 3000cuft.
Bass: I have a monster of a subwoofer in there so everything below 80hz is well covered. Setting the crossover at 80hz pretty much eliminated any woofer bottoming issues with the Ushers. However if you don't have a sub and want to blast them then it could become a serious problem.
Observation: My Usher S-520s have a very rich, powerful, musical sound to them and I'm very pleased. Audyssey wanted to set the crossovers at 60hz but I do not recommend that you go that low. Based on the Audioholics reviews and observations I recommend 80hz. I like my music and action movies loud and they have been flawless in my room. However loud is a relative term and they are only rated for 75w and I wouldn't expect them to fill a much larger room or at least a more distant seating position the same way.
BTW Usher appears to sell their b-stock on eBay.
The L&R speakers are mounted 6 feet high and aimed down at the pillows.