I'll post my replies to you at AVS that may be of interest to others here. I'm sure that there might be some opinions from our resident experts here:
I have exactly that set up - 2 X M22s that sit on top of 2 X Velodyne 10" subs (perfect height) along with a VP100 CC & 2 X QS4s surrounds. The L & R Fronts flank my TV/AV Stand & look really good this way.
In my medium sized HT room they work wonderfully with no rattling or artifacts of any kind. Good idea - go for it...
Interesting & puzzling. Stick-on isolation feet are supplied with each M22 & there are no audible problems using them that I can ascertain.
The advice that Axiom gave you is quite contrary to what I've read over the past couple of years in their forums amongst users about the performance of M22s + Subs vs M60s. Generally, the above bass freqs are very similar; however, the low end is more capable due to the powered subs taking up that load.
I am living proof that this setup works & works very well - excellent in fact for HT, IMHO. In my medium sized room, sitting 11 feet back, I normally set my Denon AVR with Audyssey at -10 Db because most movies are just too loud above that.
To give you an idea what they look like in this configuration, here are pics of my system that has been recently updated with a new Sony LED & VP100 CC. The L & R speaker setup is still the same:http://www.axiomaudio.com/blog/home-theater-pictures/?album=1&gallery=143