Yes , i refer to A-class but the curvature of the boards is not restricted, the only restriction is that the tips of the boards when full down not closer is then 1500 mm. There is some room there to play with and there are several different type of curves used at the moment.
I go with you when you are adding a spin on the boat , in the F16 you may have canted boards ( 6 degrees )and in certain conditions with the spi flying this is helping the stabilty of the boat. I am not sure if the curved board will work on a F16 ( i am going to try that one day ) because the boat is relative short and that is maybe a disadvantage.