Forgot to mention, I use 8:1 downhaul (not as heavy as Kevin ).

Totally agree with Jake, the boat shouldn`t make a difference, the event is what matters, in fact count yourselves lucky that such an event happens for you guys. I think those who do sail will find out just how well the chosen boat handles both heavy and lightweight crews. If you practice and qualify for the event on ANY spinnaker boat you will probably make the switch to the Blade quite quickly, and the advantage of having chosen this boat is that there will be very few sailors with a true advantage since it is a very new class, if the Hobie 16 or Inter 20 were chosen you`d expect the National champ in those classes to have the edge, there are still only a few Blade owners and they have not mastered their boats in a way that will make them far faster than the others.
Just an unbiased outside opinion - I`d love to sail an I-20, Blade F16, Capricorn, F18HT and an Eagle 20 (maybe a Volvo Extreme 40 too ), and would also happily crew on a Hobie 16 in a Hobie-only event, but only with one skipper.