In case it helps, here are my notes from comparing M2 with M3. This was more in the context of standalone use w/o sub but there may be some useful points. For what it's worth, if I was putting together a system for a medium sized room and was concerned about SPL I would happily go with M3s over M2s. For a small room where I know the M2s would be loud enough I would probably stay with M2s since the mid-bass is a bit flatter. The "M3s are more laid-back" point is true but more subtle than you might expect.
http://www.axiomaudio.com/boards/showflat.php?Cat=&Board=ST&Number=86248&page=&view=&sb=&o=&vc=1
>>I have decided to mount speakers on wall brackets below the screen to 1)avoid being too close to the side walls to prevent/reduce boundary effect, 2)allow for better speaker positioning and 3)not to compromise the integrity of my vapour barrier by using inwalls.
One concern with this approach is that the sound is not going to appear to come from the screen, ie voices won't appear to come from people's mouths. I find this disconcerting although not everyone does.
Best approach seems to be to have mains and center "averaging" to the centerline of the screen, eg if your center is above the screen then have the mains below the centerline so with a typical mix the sound will seem to come from near the center of the screen. Just a thought...
I would dearly love to see the sensitivity and power handling numbers combined into a single "this is how loud they will comfortably play" ranking but you would need to be a lot more nitpicky with the power handling -- today it is never totally clear whether the number is "this is the amount of power required to play average content at the loudest level this speaker is happy with", or "this is a good size of amplifier to match with this speaker", or "above this power level you're gonna be melting voice coils, buddy !!"
