I think the sub might be better located at the front of the room as the in/on wall speakers have been noted to not reach below 80hz making the lower frequencies played by the sub more placeable in the room due to a higher crossover point. I do not believe their is enough difference from M@ to the M22 in relation to this to make much of a difference although I would suggest going for the M22 just in case it does for those larger cabinet reasons you mentioned.

I would recommend three of the same speaker across the front if mounting positions allow, failing that the VP150 work.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70