On the Gath Sports website they say:

"Gath Helmets Trade Off a percentage of impact absorption for a more close fitting layer of defence to better suit high performance extreme sports."

Obviously if I smack my head hard enough to cause the helmet to break its going to hurt what ever I had strapped to my cranium. I would think there that being hit in the head by a long board would cause more damage then hitting your head on a twin tip board. But what about the kite throwing you onto something.

Anyway just double checking that its cool to use my surf helmet when I'm kite surfing. If all else fails here is my backup plan.