RE: Finsize for speedsurfing with Sonic 95 (2006)
I have a Sonic 95 too and have used it this Spring and Summer. My smallest fin is a Deboichet SL2 30, and I use it when my TR-2 6,6 is well powered up with no problems at all in chop and windswell; in perfectly flat water such as in "speed" conditions, a smaller fin would probably be OK.
IMHO, the (original) SL2 32 feels slightly smaller when compared with the stock (licensed) Drake Pro 32. I think that a 28 SL2 would work nicely with well powered up sails around 6,0, and therefore also a Drake Pro of that size would. Point is that IMHO the Drake Pro is definitely NOT a good "speed" fin, and most of its peculiar advantages that show in messy conditions are unused when sailing on flat water.
My feeling about the Sonic 95, after this season, is that it is a plenty controllable board that would have no problem when maxed out with a smaller sail (= more wind) than the 6,6 I use as "small" sail with it; and a 6,0 on flat water (no chop!) would be nicely coupled by a 26-28 fin for speed, depending on design. By sure a fin with a thin point, like an SR6b or Techtonics Goldwing or a classic elliptical, would feel smaller than fins with trapeze outlines like the SL2s or Drake Pros.