What a cool room! I love the built-in shelves for the video library!
At the risk of not paying adequate attention to your stated current wants, I want to suggest - very strongly - that your entire system could benefit tremendously from experimentation with speaker placement.
The pictures are VERY helpful!
I would try to get the mains symmetrically placed next to the TV. Having the right speaker up so high and in a corner has got to be doing very bad things to your imaging.
I would try to move the coffee table back a bit to give the center speaker a bit more clearance.
And I can't imagine that you are getting very good use from the rear speakers since they are firing directly into the headrest of the couch. If you can position them higher somehow, that would probably make a world of difference.
I think getting QS8's for the surround (side) speakers would also make a big difference.
But really - before spending a lot of extra money on speakers (height, wide or replacement) I would spend quite a bit of time positioning what you already have. I'll bet that you can achieve the spacious soundstage you are seeking just be rearranging some things.
