nice setup, I run an all polk Rti setup also, add a pair of rti4s to your gear list and we would have near identical systems. One thing I suggest is centering that center channel under screen. Also have you thought about pushing more power to your 12s. I bought a D-Sonic Magnum 1000S(525wx2@8 ohm), and now run my 12s off it and they sing an awesome song. Before that I ran them off of Outlaw Audio M2200 monos, so if youre looking to get the most out of them I recommend a power amp.