RE: S-Type 93 2006
Pretty much all the above info is correct, but please be aware the ST93 (ST's in general) can benefit in a lot of conditions from having a fin that is not toooo much a dedicated slalom design. Yes, fast and efficent are the go for ST, but running a slightly lower profile (lower AR) and more rake than most "race" fins around 30-34cm can (does) add to the "free-er" blasting character of the ST.
By design, ST (more especially ST93, the highest wind ST) concedes early planing and upwind to the iS, in return for easier ST top end range, especially downwing, thru chop and when powered. Race fins (thanks to their sheer efficency) will assist ST in early planing and upwind, and are a valid option - but throwing too much extra fin at ST (trying to make it back to an iS or equal / hard railed race board) is ultimately not so efficent - and often degrades the other end of the ST's performance range - plus the general "fun" factor (less technical, more moves).
This also takes into account the water conditions (higher winds/choppier B&J blasting mode, control conditions) the ST93 would be typically be used in, c/w (say) the larger ST's (lighter winds..and thus flatter water, more semi slalom type sailing)
I'm the totally race fin guy, but my ST93 fin preference is always "fast freeride".
Cheers ~ Ian