So your listening area is 12X12 but is open to more space right? Going with this, I think it's not really the speakers, it's your sub. It's not able to pressurize the entire room properly. I have M22s and M80s in a 12X16 area that is open to another 12X16 area in an 'L' shape and when the M22s are paired with the SVS PB13 Ultra in this space, they have a similar impact as my M80s and PB13. I ran my M22s with a lesser quaility(?) sub than your PSB and I too thought it was my M22s, so I went for the floorstanders. I then upgraded my sub and tried out the M22s with the new sub and was surprised to find the problem to be more associated with the sub than the speakers.
I have found many retail subs to lack the sheer output and smoothness of SVS, Axiom, Hsu etc., especially in the lower to mid price ranges.
Having said all that, I do still find a touch more impact/fullness with the M80s/PB13 than with the M22'/PB13 but it is something only someone that is very picky about their sound would notice and I would think most likely only under A/B listening tests.
If you are not really looking to upgrade the sub then yes, you will get more from the M80s than the M22s, especially in the lower ranges and sheer SPL output. I now fill my entire room with sound from just the M80s/sub(sub not really required), where I had to use multichannel stereo mode/sub to really fill up the space when running the M22's.
