I'm thinking of getting the acoustechs as well. With the surrounds having 2 drivers and 1 tweeter, all pointing in different directions, you have 1 driver pointing through the rails, away from your listening position. Do you hear anthing back there? Does it add to the surround effect? What if you mounted them at an angle where the wall and ceiling meet, basically pointing them down towards your listening position?
My problem is that there is a full height wall right behind the couch, nowhere to mount the speakers behind the listening position.
The 5x9 in the back is just a passive radiator, so they don't throw out the same sound levels as the drivers.
If I had a wall right behind the couch, I'd probably try orienting the speakers exactly opposite of what I have - with the angled tweeter poiting towards the back wall and the passive radiator pointing straight forward - having the tweeter bouncing sound off the back wall would probably diffuse the sound nicely.
Doesn't hurt to try them in a few different arrangments and see which sounds best to you.