I chickened out and did not go out through the surf last weekend. What helped me make my decision was that I ended up taking my son out his first time on a yak. Dealing with the surf the first time out may not have turned out so good. Better to get him hooked then dunk him.
I suppose I was not very clear in my leashing of the mirage drive in my original post. I have seen a photo of how some guy has a leash on his drive similar to using a leash on a pole or paddle in case it goes overboard for some reason. I mounted a padeye on yak under the mast hole to clip a leash to but not sure where to hook up to the mirage drive while underway.
Picked up the ST Turbo fins and can see how that set screw may back out if the mast rods are not installed correctly. Need to make sure the set screw is sitting exactly flat against the notch to prevent the mast from working back and forth and becoming loose. Should work fine by following the instructions.