Jeez, Randy. The QS8 is extremely forgiving in where you put it. I don't think its orientation is all that important -- it will spread the sound out well whether it's vertical or horizontal. The main consideration here is that the T-brackets won't hold it securely to the ceiling.
Jason,
If you tried to mount a QS8 to the ceiling using the T-bracket, the slots on the QS8 would severely torque the tabs on the bracket because they are located near the edge of the cabinet. The opposite end of the cabinet would pull away from the ceiling because there's nothing to hold it up.
