With a sufficiently large version of this, why couldn't you jump, crouch, crawl, and lie down? The system would move you back towards the center between jumps.

A remaining missing piece is possibly some type of Galvanic Vestibular Stimulation system. Tell me if I'm totally off-base on this, but this seems like a technological achievable problem.

I'm not saying it's perfect (you can't simulate scrambling over a rock, for example), but it would enable a pretty wide range of movements.