Jeez why did they even recommend the EP500 with my stuff if it is so much of an overkill?
Hmmm, its always hard to tell what someone is looking for. Any of the EP350/400/500 are quite a step up from the 175 and will produce a lot of volume in a small room. They represent the current state of subs. The EP175 is quite dated.
The other thing that you get is much better performance below 40Hz. You will notice it on classical music and any thing with a lot of synth. I'm waiting for you to play your first movie.
Unfortunately you cannot separate the higher volume from the better performance below 40Hz in most subs You get both or neither. You don't need to use all that extra volume you have, and you will begin to appreciate the better performance below 40Hz with movies and any music below that range.
As for the EP175 being a better match for the M22s, thats no more true than saying its a better match with the 60/80. Maybe if you are playing only music with content above 40Hz in a small room, but in any other situation I would disagree.
Get your sub dialed in to your taste, listen for a while, and then let us know what you think.