RE: s-type 115 06
I also own this same board for over one year now and it is really really really fast.
Back footstrap position is important. Outside position is for slalom sailing but does need slalom fin. Inside is for fun & jump and than stock fin is very good.
I found also that it is much more important to have the sail rigged properly comparted to the older, longer type boards. If sail is not rigged right on this S-type, also there can be a tendency for spin-out.
Ciao for now,