Another outsider view :P
Nacra could built a F16, but if they were to look on these forums they could be off put, most of the threads end up turing into fights bettween parties (parties that are not obviusly F16 or non F16 sailor) meaning that it gives the F16 class a look of friction between sailors and possibly a difficult class to deal with. Nacra could possibly go to AHPC and disscuss with them of setting up a new class of 120ish kg boats that they can both easily market and manufacture, and pgp's posts on the F18 forum will have not done the class any favours.
Before you start ripping me apart, if the UK youth catamran was still the Hobie 16 and not the Spitfire (which might fit in the rule actually) then I would seriuosly consider getting a F16 as I would have to get a 90kg crew to sail a F18!