I've used them...not a big fan of them. I may start using them in the Yak more though. My thought process being that "Swinging for the Fences" in a Yak will probably get me more wet than anything else.
"If you're arguing with an idiot, make sure he isn't doing the same thing."
Sometimes if its very windy and the water is real turbulent they do not work as intended. At least that has been my experience sometimes. Overall though have worked majority of times!