Yup, I recently joined the club
Managed to flip the Island the other day. I launched in the surf in the Atlantic with no problems and pedaled out to where it was deeper and calmer. Well, I got bored because there was almost no wind so I took to surf riding with the sail still up.
Was doing pretty well, but like the tune "Flirting With Disaster" you know what happened next. I caught a decent wave but when I turned to go back out an even bigger wave curled up on me while I was sideways. It was only about 2feet but it lifted one ama high in the air while it buried the other ama into the water and over I went.
It was a slow motion affair and it was more like sliding out rather than be tossed out. The boat never did a full turtle and none of the arms folded up. Boat was on its side, perhaps so because I quickly grabbed the mast to steady the boat. I dumped the water that was cupped into the sail and gave it a heave-ho and got it upright.
I was not hurt and the boat was undamaged - I did startle a few nearby surfers however. I am a little glad that I did flip the boat as the experience is a valuable one.
I continued surfing until the wind picked up and was more keen now on making sure to point nose of boat into waves when going back out.