RE: q for ian fox difrence drake fins pro and sr6b
The DrakePro is softer and in general a more versatile fin offering a wider all round performance range. In general, heavier guys who sail with hi fin loads will find the DrakePro(in slalom sizes) becoming a bit soft earlier than average weight riders, especially when pushed hard in chop/swell. However in light winds the Drake Pro still has some advantages (ease of sailing, speed at various angles) even for the heavy,hard guys.
SR6b is a stiffer fin, it does perform better under higher loads (heavier/harder sailing guys) and it does have a marginal top end advantage over DrakePro in mid to hi speed conditions, but does not have quite the same bottom end, upwind or verstaility as the DrakePro. Many riders also find the DrakePro resumes easier after a jibe, SR6 is a bit more technical.
In your case, if you're loading the fin a lot and looking more for top end speed than angle/versatility/recovery then a good combo could be Drake Pro in lighter 9.9 / lightwind 7.8 and SR6 in powered 6.8/5.8 conditions.
Also worth noting we continually evolve the fin layups for the slalom boards to fine tune and refine the best "allround" performance for typical sailors ; this means the stock fins are slightly different for year to year as they are focussed and refined for versatility more than "peak" performance in any one criteria(which would compromise the allround character..)
Please let us know if you have more questions .
Cheers ~ Ian