hi guys, thanks for your comments, please find requested answers :
Concerning precautions, I took as many as I could because I do this alone and it can rapidly become dangerous. I knew well the place and its weather conditions, I had done the tour by foot before, to identify difficulties such as rocks or places with important swell in certain wind conditions, and to see at which points of the tour I could "land" in case of difficulty. Then I waited for a day with light wind from right direction, and forecast of steady wind througout the afternoon. On that day I chose a prudent timing, took a waterproof backpack with water, food, cellphone with sea rescue number, wore a shorty despite warm weather, carefully checked gear.
Concerning sail choice, it was in fact mainly practical : this particular 9.5 was the only one to have sufficiently short luff (528) and boom (246) to fit on my available mast and boom. Apart from that, I suppose it may not be the best choice for a raceboard, as you would prefer lighter, more powerful sails, but I like it. Notably, it is extremely easy to rig, which was a pleasant surprise.