I was thinking about getting a pair of these. I was wondering how well they grip on slippery rocks and if they are thick enough to protect your ankles?? Any input would be appreciated.

Sorry, do not own any, but boots are one of those things I'd not purchase sight unseen. Get to a dealer somewhere with ones waders in hand and try some on. Not the case, however, if I have experience with product that I know will be sized correctly and is durable.