I would still opt for the tower speakers LazyJ.
I think you can get away with the QS4s for sure.
Pluses/minuses on the centre channel but i think it would work fine.
As Alan said, we ppl often tend to turn up the volume for movies and that new dimension room is still medium sized volume to fill with sound. I certainly agree. I play movies alot louder than music (most of the time).

"Those who preach the myths of audio are ignorant of truth."