Tony,
The QS8s do not require pointing down, because of their multi-directional propogation. You can always try a pair using a couple of stepladders or an able assistant to support them at the sides and back while you listen and compare the results.
Since they rely on lots of room reflections to achieve the envelopment, the room itself is a variable, however, they tend to be forgiving of asymmetrical placement. My own QS8s--sidewall mounted--are not at the same height nor exactly opposite each other. My couch is against the back wall and in my room they sound great. Adding an additional pair above my couch for 7.1 did not significantly change the envelopment, but that might be quite different in other rooms.
Regards,
Alan
