Unless the focus and metering are done without the mirror reflecting the image. In other words, the focus and metering "sensors" are arranged differently.

That's not the problem. The camera needs the mirror to be down to focus and meter, so without the mirror constantly flipping up and down the camera will lose track of focus and metering, making the higher fps useless, because the shots will not be focused and correctly exposed.

Unless I'm wrong again, looking at the patent concerning the mirors retention for 14 fps, I wonder why they just don't let the main mirror come down every 2 or 3 shots, rather than design such a complicated mechanism... The eye/brain wouldn't even notice it.