My riding buddy and I both bought the RU Outside sonic boots last year at one of the snow shows. He stepped in a fairly deep puddle with his this year, assuming they were waterproof. They are not.
The Sonic boots are by far the most comfortable boots I've ever worn, but I'll be kicking myself for buying them the first time my foot gets wet. I'm starting to think nothing is really waterproof besides gore-tex (besides pure rubber I guess).