I have to say that the walkable cleat idea is wonderful, however, the execution leaves a little to be desired. First, the standard issue yellow covers seem to be the worst, because that color fits less well than any of the other colors available, so if you loose a yellow cover, by all means replace it with any of the other available colors. They will stay on longer, last longer. Still not perfect, but barely adequate. I also ordered and installed the surround base, and the thin metal sole protectors in hopes of keeping the covers on for longer by stabilizing the edges better. Here's hoping. Love the pedals regardless, would be difficult to go back to anything else.
I have these cleats on 2 different kinds of shoes, Sidi and Giro, and the cleats fit well on both brand of shoes. I put the surrounds on the Giros, with the black walkable covers and the sole protectors, and feel this is the best setup for reliability. We usually spend 2-3 months in Girona, Spain, which means I take extra cleat covers with me in case one is lost (yes, it happened to me), glad I had extras as nobody carries these over there.