Cat bridgedeck hieght
Slamming, et al. is a function of the heading, how overloaded the cat is, etc. Find the right seas and any boat is uncomfortable.
Having said that, Cats are very sensitive to weight distribution and weight in general. Make them too heavy and they''ll bury the hulls instead of floating over the waves. Having said that, if the intervall between waves is just right, some interesting things can happen.
Many years ago we were motoring up to Swans island in a flat sea on our Prout Snowgoose (37'' cat with a ~16'' beam). A stinkpot (i.e. huge motorboat) came the other way. Mum was below making breakfast when we discovered the that wake of the stinkpot was perfectly out of phase with our hulls - that is, a through was swallowing one hull while a crest was lifting the other.
The net result was a very violent shaking motion that got everyone woken up in a hurry... Naturally, this never happened again for as long as we owned the boat. Did we slam in steep short seas? Yes, but the questions are: were we safe (yes) and was it necessary to stay on such a heading (no). Similarly, a particular heading on a Waquiez 43 monohull made me so ill that I had to stay on deck, could not even look below, while I would have been fine on our Prout Escale.
So, the evidence of slamming is not what I would question but how easy it is to get the boat to slam in the first place. When we sold our Prout Snowgoose and took our gear off, we were amazed how much more responsive and easygoing our catamaran became - evidently she was very sensitive to being overloaded. Lesson learned, we keep as much junk off the Prout Escale we own today as possible. That makes the boat as much fun to sail as it is.