I would second the comment about the footstrap holding my back foot when the boat decelerates rapidly. The chicken lines work better, but sometimes it's not practical to rig them (for buoy racing, as an example)

I have been washed out of the back strap once or twice, but managed to stay with the boat using the mainsheet/spinsheet (sometimes it wasn't pretty, but worked).

Maybe a combination approach? Traditional strap at transom to keep you getting lurched forward, and some version of the skyhook thingy near the beam to help you from getting washed off the back?

Or maybe just velcro shoes?