Hi Russell,
In my San Francisco residence I have the Ultimate 545PXs in a room very close to the dimensions of yours. I am extremely pleased with the sound. The volume of the room in cubic feet is the critical factor in determining minimum panel size. You can always go bigger without a problem, so long as they fit in the room! This opinion comes directly from Dr. West.
I have a second system in my country residence in a much larger room with the Ultimate-1PX panels. The sound has the same character, but presents a much larger sound stage. The 545s would not do as well in this room, as the radiating area of the panel in square inches is not adequate to activate all of the in air in the room, which is an important factor in giving Sound Labs their exceptional quality.
You are welcome to visit and hear them for yourself.
