Never seen it before, but seems like a more useful evolution of the SE Sport 200 Hydrofoil that I tried back in the day. It didn't do a whole lot for me performance wise, but the Hydro-Shield one you linked to looks like it has a shot of protecting the prop at least, even if it doesn't improve performance. I would have probably given it a try on the first lake I boated that had stumps and where we beached on sand bars more than we do now.
I've had the leftover holes in my outdrive for years now! I keep meaning to get around to filling them with Marinetex or similar, sanding and painting...but since the boat is now 22 years old, I don't think it's going to happen.