I appreciate your thanks . It is time consuming but with passion , every discussion is pleasant;
so, about 12m vs 15m ( without having tied the 15m):
- reminders : I am lighter than you with only 60 kg ; I use a large Ketos wing for light winds ; I have pretty good light wind ride skills (
I would never have said that if it was not to try be as accurate as possible, please forgive-me this pretentious assumption)
- compared to a Speed3 dlx (which should fly with approx same wind as Speed5, in theory but not tried), I can ride "easily" on water as soon as the speed 3 stays at zenith on the beach; I can go approx 1 knots lower but requires special technics for the waterstart; the Pulsion stays far better in the air, and this difference allows you to swim-out from shore and keep the kite at the zenith even with the 1 knot draft of deep water. its stability on front lines allows you to keep concentrated on the HF management
- hard to tell the impact of your wing size, but for your weigh and if you know how to waterstart-loop, I would guess that you will ride as soon as the S5 stays easily in the air on the beach, which I call 6 knots
- if you want to play with the elements and reach 4 or 5 , the 15m will do it, the 12m I can't tell with your configuration. Benoit Tremblay is 88kg and rides in about 6 knots from his reports.
- top end of the 12m is about 17knots I would say for me (no transverse rides at this high wind), so I would say 19 for you on a hydrofoil; my guess on the 15m would be 14 knots for you.
- both will allow you to ride "normally" from 6, but if you want high speed below 9 knots, 15m will logically go faster, in detriment of manoauvrability for transitions.
- for your weight I would bet that in term of comfort, the 15m is better up to 8 knots while above 10 knots the 12m is better (more agile and wider wind range).
So ... not sure to actually help you, but in a nutshell : if you are looking for absolute low end or speed and be ready to swim sometimes, go for the 15m ( and make a report ! ); if you want to freeride from 6 (or at least the same power as your s5 but with better zenith ability and agility for waterstarts and lulls, my guess) with a all-round and more fun kite that need to cover a large wind range and that still safely stays in the air for 4-5 lulls to come back to shore, go for 12m. A friend of mine, same weight as yours, bought the Pulsion 12m and confirmed he get more pull from Pulsion in light than S4 Lotus 12m and said he will increase + 50% its riding time vs Lotus since the 6-8 range is very frequent on his spot.