I have hit something with the t-foils...

While sailing the Stealth, I hooked a crab pot line with the rudder. Neither the transom nor the rudder box "gave." Instead, the rudder pin popped out of the lower fitting and bent. The "repair" consisted of simply replacing the pin, so it was really no big deal. Perhaps John P. can speak to whether this was a cleverly designed phenomenon.

Hitting the daggerboards on something immovable is a bigger concern, since they're longer, trunked in hull and, being in front of the rudders, will hit the object first!

I actually can think of a lot of occasions where the cassette up/down configuration would be quite handy. Farrier has a nifty combined mechanism on some of his trimarans--the blade slides up and down and the rudder box also kick up. (Too bad that system won't work for T-foils.)