Boyer produced gave a statement about canted boards a few years ago along the following lines :

Mk 3 A-cat and Mk 4 a-cat are identical in all but canted hulls and canted boards. The speed of both is identical but in the midrange of windspeeds the mk4 has a slightly better steering characteristic.

In other ranges the mk 4 is fully identical to the mk3 and in some cases the steering and handling is slightly inferieur.

Wouter