The Ultralights look like fun and I enjoyed watching them over the reef up north the other day. They are a little noisy and you definitely know they are around.
These are serious machines which could be very dangerous if some thing goes wrong and that means over the water or land. I would not want to be in one if it decided not to fly for what ever reason.
Years ago, I'm sure they are better now, a brother to an engineer I worked with was killed when his ultralight came down after its engine stalled. Even hitting the water would be tough from most heights and they don't look too buoyant to me.
Still they look like fun, but I think I'll pass for now.