It's my understanding that the closer to the corners you have your speakers, the more increase in bass you'll have and muddy the sound of your room. You didn't mention your ceiling height, but I'm guessing you have your front LRC positioned the way you do because of the size of the screen.
What I would try before replacing my center, is repositioning your front speakers and subs disregarding how they affect your picture to see if you can get the sound right first. Try using just the single XXL center and get it off of the floor to ear height or up a little and pointing toward ear height. Move the subs out of the corners. Also, I bet those T Refs will sound a lot better a little farther out and away from the side walls, too. If the clarity improves, you might want to get an acoustically transparent screen and/or replace the false wall.
Depending on how well the T Refs do, I'll bet Sandy will come out with a matching center like he did with most of the Triton series.
My HT setup is in my living/family room/kitchen and the acoustics are pretty bad. I'm hoping to get a better room for it soon.