The problem: the room measures 17.5 feet by 11.5 feet with ten foot ceilings. The listening position is on the short wall (11.5 foot maximum to the front wall and front speakers). Ceiling mounting the surround speakers won't be possible. Side mounting the surrounds also won't work (one side opens to another room, the other side is a wall of glass with a hallway to another room). My only option is the rear wall above the seating position. After a lot of searching, my best bets (to this point) are the Axiom QS-8 Speakers.

The associated equipment: I have (and love) a pair of Paradigm Active 20s and an Active CC center channel. The rest of the equipment will be added when the room is complete.

The questions: Will QS8 be in the ball park for timbre matching with the Actives? Where and how high on the wall should they be mounted? Will I localize the surrounds given that one driver faces down toward the listening position? How well will the surround effect fill the room (I'm shooting for maximum envelopment...aren't we all :-) ). Are there any other speaker choices or mounting options that would better serve my needs, given my placement limitations?

Any and all suggestions are appreciated...the sooner the better as the wire needs to go down before the tile...which is next week.
Thanks in advance.