You also might want to drop the surround channel levels a bit. I find that in the real world the center needs to be increased a bit and the surrounds lowered a bit.
I suspect the main problem is the in-ceiling speakers. Even with ones angled forward, you're still getting dialog that's mostly reverberating around the room. "Expert" installers absolutely love to use in-ceiling speakers due to the low visual impact. The problem is, they're terrible for...