Catamarans that have flatter shallower hulls tend to have more initial pitch stability because their longitudinal metacentric radius is larger. If you divide the second moment of area of the waterplane (at the LCF) by the immersed volume you get a good approximation of the metacentric radius at small pitch angles. With flattish hulls the center of buoyancy moves forward farther with the same change in trim - which means the longitudinal righting moment increases more quickly.

For most catamarans the effect of the flattish hulls on pitch stability is just hydrostatic.

- unrelated about the Tornado - I think their hull design is one of the main reasons they are so fast!

talk to you later
have a great weekend
-colin