The thing with absorption is unless you are actually measuring RT60 vis a vis surface area to figure just how much you need, it can be hit and miss. I would go with skyline diffusors in the center ceiling. They are light and easy to install.
My kids are always yapping, Dad what was that? Dad, pass the popcorn. Mom, scratch my back.
I need a center!
I was watching Young Frankenstein which is mono and the Ls and Rs did fine, not as good as having a dedicated center channel but phantom works, at least for the one sitting in the middle. Dialog might not be so clear from the sides as it will be mixed with L and R front effects. The people in the sides will also have to process the sound of the later arrival time of the opposite VR-4 SR. Multichannel music is less of an issue, much less.
Nothing like having what amounts to three identical speakers out front for movies though. The Visiun is large however and will likely need a custom stand. I lack the real estate to have a HT rack to the side like you do so I ended up having the screen much higher than usual. When we watch, we look like a bunch of astronauts waiting for launch.
