I don't have a specific answer for you John, but I ALWAYS format my cards. I don't think I have ever used the Erase function, and I have never had a problem with my cards. I know another woman, who had never even heard of formatting her cards, and she has never had a major problem with her cards either.
I have always heard that formatting the cards, in camera, was the best way to erase the, and that's what I have been doing ever since I got them.