I can tell you what I observed although admittedly I didn't really approach it like a science project.
In general, I found larger speakers, with more drivers, need a bigger room and a greater MLP. Larger rooms do not necessarily need larger speakers. If you want to sit 12 feet away from your fronts, M2s are good enough with good subs like the 500s even in a 4,200 cu. ft. space like mine. In a 2,000 cu. ft. living room, floor-standers are a total waste of money and will give you more problems. This goes for music and movies but I will tell you that active LFR1100s add a lot to movies. I could not say that about M100s vs. M2s as fronts.
-- Bass --
Any passive floor-standing or bookshelf had attenuated bass response when moved away from the boundaries. No surprise there. In my living room, the M2s were the only ones that played non-bloated bass. M50s were a somewhat close second. In the basement, the bass response was good from all passives as long as they were moved into the room a few feet. They all still needed XT32 correction.
The actives are very different. I didn't notice any bass bloat at all. Quite uncanny actually. I suppose maybe they were tuned for boundary placement but even so, when I move them away from the boundaries, the bass does not change. Not sure how this could be. Also the actives don't need any XT32 correction. There is no difference between corrected and uncorrected to my ears.
-- Imaging/Soundstage --
The M2s were the easiest to image out of any passive. I found as I moved into larger speakers, it was more and more difficult to image and I had less degrees of freedom. Ultimately, for the best imaging and soundstage, they all need to be into the room, forming an equilateral triangle with the MLP. You can move the MLP closer to hear more of the speakers rather than the room. I find this too "in your face". You can move the MLP further if you want to experience the soundstage as if you are more "in the audience". This is how I prefer it.
The actives are quite different. In my living room, I really could not get soundstage width beyond the speaker boundaries. I was sitting 10 feet away and they were 10 feet apart. The size of the actives was getting in the way. The M2OW are far better in that regard. In my living room, I am giving nothing up with the M2OW compared to the active LFRs. Yes, the bass out of the actives in the living room was something else entirely but what I have, with my two crappy subs and the M2s, is very satisfying also. The basement is a different story because I am sitting 14 feet away and the actives are 12 feet apart. They're only a foot into the room. The size doesn't get in the way there, and with well-recorded material, they completely disappear acoustically. They really don't need perfect recordings. Yes, music with them is amazing but it's the movies that totally surprised me. No center needed and the experience can't be matched even with the M100s.
It's the first time in 13 years, and I am no longer wanting more out of my speakers and subs. It took a hell of a lot of experimenting, and money, to get here.
