I really do see a difference in between a foil and a wing. A foil renders the whole measurement system of a cat invalid as the submerged part of the boat is completely different. Whereas a wing is in theory just the most efficient sail. I don't see any reason for a development class to abandon such a direction, if it shows valuable. Even if it costs say 20.000$. That's what development classes are for. Wanna sail in a "cheap" class? Don't go for a development class. Maybe A-class isn't development any more??