Hi Wouter, Dermot, John & all others interested :

Wouter, what I meant when I wrote "There`s not much between Spitfire & Stealth R on paper, good sailing skills could overcome the minor difference." is exactly that : the boats are so even on paper that they could both be regarded as equal speed potential, so could be raced against eachother as per the F16 ideal i.e first in wins.
I find it a little surprising that the Spitfire class has "barely heard of F16" and that they don`t really see the need to be associated with the class, as when I look at the list of boats that are included in the F16 class by the Grandfather clause, the Spitfire & Taipan are listed as being included. I would have thought that this would imply their co-operation & inclusion in the class, including it`s inception & development, which seems to be contrary to what is happening.
Note that I says "seems to be" as this is what I am concluding from other poster`s opinions or viewpoints, so my perspective could be wrong - the earth is curved, so I can`t see what`s happening over there, and rely on info from those closer to the action.

What I see happening in the long term in cat-sailing, especially with the predicted (ISAF/Texel rating) performance of the F16 being so close to F18, is that as cat-sailing continues to decline world-wide, one-design classes will fade slowly, or be superceded by the latest designs as they appear. What will succeed is a Formula-based all-inclusive class, to the point where if F16 & F18 have equal ratings, they may one day become one formula class. I could be wrong here, perhaps One-design classes will get stronger & formula racing will die out, who can tell ?
The disadvantage of one-design classes is that as they are introduced into the market they grow rapidly, normally at the expense of older o/d classes, and have a lifespan only as long as it takes to introduce a more attractive / faster / more organised o/d class, whereas formula rating classes ensure a longer lifespan of o/d classes that operate within the formula framework, since new boats introduced into the class will, by design limitations of the formula, have very similar if not equal performance.
This can only be good for both parties.
Regarding changing the Spitfire to suit F16 class rules, there is no need at all to do so, since the ratings are so close. The boat`s additional sail area is offset by the additional weight, so the performance should be close anyway, no need to change anything. In fact, it would be very interesting to see how the "heavy with more horsepower" option compares with the "lighter with less sail area" option in real terms.

Cheers
Steve