Another view on platform stiffness from someone who might have a clue about these things. This is from a recent published interview with Bob Baier, current German A Class number one and current European champion.

"In my opinion, what is crucial here is simply the honeycomb construction. Here you have much greater stiffness than on a foam boat. Although I am no boat builder, I notice this in the steering. On a stiff boat, one has the feeling that the boat is moving as a single unit. The hulls do not work against one another, rather they move synchronously through the waves, which is how it should be."

The class rules in F16 don't seem to define or measure stiffness. So this seems an area of unrestricted development which would be persued by builders over time. The Viper seems a step ahead in that area. It has certainly provided some impetus for F16 in the so called land of the dog. Before it came along F16 was going nowhere here.
Cheers