RE: S-Type - Fin size change
Ironically, the answer is partly also AR - as in Aspect Ratio.
The new 2007 fins are a higher AR, so their mechanical size ("cm") is bigger than the older fins "cm" for given performance size. That applies across the whole range of that fin model/family - and correspondingly where used on the ST range as stock.
The reason the 2007 ST93 is proportionally longer (again) than the other ST models is that we also decided to spec the stock fin to be a "performance size" (range size) larger than the previous ST93 generation. This was based on the feedback that many riders were using more the 32cm size previously in this board, more often than the old stock 280 lower AR fin.
Despite the apparent large difference in "cm (mechanical )size", please be aware the performance size of the new 340 is about 1 to 1.5 "fin sizes' bigger than the old model 280, rather than the 2 to 3 sizes bigger the cm rating (alone) would imply.
Cheers ~ Ian