RE: For Ian Fox: ideal fin size comparison for Sonic100/iSonic94/101
The SL2 35 will be a good choice : If the SL2 35 is perfect for you now on the S100, then it will remain so on the new iS94 (which although a big smaller by volume actually carries a bit more tail width and fin drive - and so can handle a little more fin in theory - but in practice it's ideal with S100/S95 derived fin tuning.
If you decided to go the other way and choose iS101, then again an SL2 35 will be an ideal mid to powered 7.0 conditions fin. yes, here the iS101 can handle a lot more, but for sure for slalom speed, it's ideal (and faster) in the 32-36cm range for racesails around 7.0m with 80kg.
In any outcome, you can't really miss. Go for it.
Cheers ~ Ian