Knock on wood I've not been there yet.  On the paddle issue, we had outfitter paddles one year and my son picked out a brand new one and it split not 50 yards out of PP.  Kept the pieces and used the spare but always thought we could splint a broken paddle.

Ever since having gone swimming to retrieve a canoe, that has been a bigger fear - like what do you do up a creek without a canoe?

Certainly a sprain or bone break is probably the biggest danger, and I suppose that's why I started carrying a spot, starting on a solo.  With two or more, I assume there is some solution to even a badly broken bone.