1. Single hull kayaks have an advantage in surf, in that, if they get side-on to a wave, you can lean into the wave, bracing with the paddle, and stay upright. Because of the amas, the AI is always going to be more or less at right angles to the surface of the water, which makes it much more likely to be tipped over if it is on the face of a wave.
2. Arno capsized his AI in surf and ended up with the mast imbedded in the sand: viewtopic.php?f=70&t=18539&p=91062&hilit=capsize#p91062
3. It's easy to rig the mast on the water.
4. I would have thought the tramps could only make things worse.
You are more likely to have problems coming in through the waves than going out, because the boat is more likely to get turned sideways being pushed from behind and the rudder is ineffective when you are travelling at the same speed as the water around you. Interestingly, Yakass told me that the guys from the Transparent Sea
expedition always got out of their AI's and swum them in through the surf and they are mainly pro surfers.
That said, the waves in the video look manageable, but you wouldn't want them to be much bigger than that last one