I never understood the need to block the UV. For us, sure, but for the corals that bake under the sun all day long without a tree for shade...never understood that.
I'm sure they would take some acclimation, but I plan to do this in my room addition for my 180 and I plan to leave them as open as I can to allow the entire spectrum of light in.
Mother Nature has been keeping corals in her tank much longer than we have.