I understand your comments regarding knee braces. I envision a sort of circle formed by my pelvis, legs around each side, and closing at my heels. Based on your "crush against the footbrace" comment, rotation is thus a "rotate left" or "rotate right" (there's my machine code mentality again) of that integrated unit.
I seem to have a little play somewhere, because when my pelvis is rotated in the seat I don't feel much change in my leg/knee/foot interface on either side. Everything is still tight and snug.
I may just learn to live with it. Always looking for that last bit of improvement, you know....