RE: S-Type : 104 vs 93
I have the straps on the outside, full back. I mostly sail the ST93 with the 6,6 (32cm fin) and the 5,4 (26cm fin). Note that I'm 67kg.
I also ride it a couple of time with the 4,7 because the wind picked up suddently, but it is not my goal with this board.
At the time, I haven' try the central strap settings.