I'm curious... Why foil the rudder? We're not talking about foiling the entire boat to raise it out of the water, just the rudder. What does creating lift on the rudder accomplish other than raising the transom a bit? I don't see it as improving helm performance or balance. So if you want to raise the stern, why not simply move crew forward? At least on my Prindle, if the crew is near the front crossbar, I can raise the stern quite a bit.

It just seems as though it's a complicated design which introduces another point of failure (and expensive failure at that) for very little gain or at least a gain that be gotten from simply repositioning the crew on the boat.