Hi ser182,
Given the ratio of HT to music, I believe you'd much prefer the sense of envelopment that the QS4s will give you. And I think you'll like them a lot for music as well. I love my QS8s for movies and music. Besides, the M3ti's are not a close tonal match to the M22ti's. If you want to get direct-radating surrounds, get the M2i's.
And do put them to the sides, if you can, not the rear, although the QS4s are very accommodating and will work okay at the rear. But the main surrounds are intended to go to each side of the listening area.
Regards,
