I'll be happy to update you on my experience, with these disclaimers. My sonic memory of my original audition experience has faded some, as you can imagine. And I've never listened to the M20's.
I also need to point out that I haven't heard a Revel I liked except for the M22. People tell me it has the same tweeter as the F32, but it sure didn't sound the same. Something is different inside. The F32's tweeter was too shrill for my ear, and the highs didn't blend in with the midrange. And in small to medium rooms, I could detect which drivers were producing which sounds. The same goes for the flagship Revel or the near-flagship... I can't remember which one. (Sort of Revel's answer to B&W 800's or 801's or 802's.)
The Paradigm S4's and S2's excelled in dynamics and bass extension for their size and price. There isn't much difference between the two other than bass extension and loudness. I would call them good speakers, and wouldn't be ashamed to own a pair of either. But as you say, the midrange is paramount and the M22 beats both rather clearly in this regard, and the small B&W's by a mile. The M22's also were quite balanced and coherent over all frequencies down into the low 50's, high 40's range. They played Led Zeppelin quite well... the pounding drums and electric bass sounded more like real instruments than from any other small speaker I have heard. I don't remember imaging as being the Revels' strongest suit, but it was there, and the setup may not have been best to evaluate this characteristic. I would call the Revel M22 at least a very good speaker, perhaps excellent in some respects.
My Merlin TSM-MX's are altogether different. They make no pretense of going for the "bottom octave," as Bobby P. puts it, but are geared to do music in their range more purely than anything else their size and price. To my ear, they do. You have to get right up on them... like, inches away, to detect which driver is producing which notes. There is a seamless handoff between tweeter and the mid/bass driver, and I have yet to hear a more coherent team of drivers and internal electronics. The tweeter is smooth as silk. TSM's are balanced in their intended range. They image like crazy. They make the smaller B&W's midrange sound muddy and boxed in. No comparison. They are excellent.
M22 vs. Merlin TSM-MX? M22's will have the edge in power handling capacity, bass extension and dynamics, and in loud "rocking out." I think the Merlins would win in every other respect. They make me enjoy listening to music. I have no desire ever to hook up my B&W CDM 1NT's again.
