RE: Me too..
I too would like to ask the same question. I will be racing a 160 this season with Vapor 12 & 11 sails. I currently have an R17S+8 (scary fast on flat water with plenty wind, but little lift in light wind) and R18S+8 (better in light wind; but I find it a little hard to get really good performance from this fin). I weigh 95 kg.
I consider ordering a Deboichet R19 +8 for light wind use, but am unsure which stiffness to get for the 160 and my weight and if this fin in general is the right choice. Otherwise I will probably get a R13S+8 which I know works really well with the 160. IS the R19 even better?