RE: S-Type 93 2006
You're right, the little s-types can be used as slalom boards just a step behind iSonics, while rougher the water, less difference between them. Of course trimmed with footstraps on back and outside position and slalom fin.
I tested the ST 104 and 115 and iS 115 with the same fin(34 drake slalom pro) and sail(SSR 7,6). The average speeds of iS were always better than ST but the max speeds deep downwind were better with ST.
Only upwind there were big difference, much better on iS.
As you said, perfect connection between freeride and pure slalom board.