Wingman and RonDon--I have not heard of Frenchy Ludo's either. If either one or both of you go, would very much appreciate your review!
For French on the Dutch side, you also have Antoine's, which is in P'burg. We have been to Antoine's, Moulin Fou and Mario's. We probably enjoyed Moulin Fou the most, but I will confess, some of that might be as a result of our company that evening, which was delightful.
Antoine's would be my third choice, because of location, unless you want to go for an elegant lunch on the Boardwalk and people watch, which is what we did. If you go to Antoine's, make sure to pre-order the soufflé!!
For Grand Case, you might check out the thread about water side restaurants in Grand Case. Unfortunately, not much open water side now. For land side, my personal preferences would be Bistrot Cariabes and Le Cottage. You can't go wrong with either one.
Otherwise, on the French side, we REALLY enjoyed an outstanding lunch at Tropicana, at Marigot Marina. Personally I don't feel particularly safe in Marigot after night, but I would definitely do lunch there again.
Enjoy!