Like Eric said, the QSs will give you a more diffuse sound. It will make the surround effects harder to pin-point. This is actually a very good thing for surrounds as it makes the experience more realistic and convincing. I had direct radiating speakers as surrounds and I now enjoy the QS8 effect much more.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated