Depends. If you do a lot of listening to SACD and DVD-A, I would think the two M22s as rear surrounds would be better. If you listen to regular CDs and watch a lot of movies, the 4 QS8s might be the better route. You won't suffer, either way. The size of your room might also be a factor.

Jack

"People generally quarrel because they cannot argue." - G. K. Chesterton