Thanks for the responses guys!
I took my screen down and set it on the floor about two feet into the room and ran some videos, AT "Might" be a possibility maybe.
I don't want to use a phantom as it limits the 4311's DSX processing options. Well I would only have to raise the screen two inches to fit the Tempest under. I am leaning towards trying to go AT, I get that having all the speakers on the same plane at the proper height will always be best. I guess I just want to understand a better perspective of what I would be sacrificing putting the center Tempest under the screen, is it going to be hugely messed up or just not the best but still acceptable. All other things being equal are there different issues with this type of speaker vs what I have now as far as the center channel in this placement? I guess I am thinking its not ideal now and not ideal with the Tempest but the Tempest is still better! I appreciate the opinions guys, so keep em coming and be patient with my novice-ness with these speakers!
How does it limit DSX?
I would just try phantom with L+R, you have literally nothing to lose, its not like its cheaper to buy all 3 speakers at once.