Originally Posted by Flannigan
IMO you should always be polishing, or at the very least be using a paint cleaner after claying. Claying will, most of the time, leave some marring. It may be hard to see on certain colors, but it's usually there. I know that the Ultima clay block mars, that is why I only use it if I'm polishing after. Otherwise a milder clay follower by a paint cleaner will get the job done on a wash and wax.
I have seen some marring after clay, but what I saw in the pictures and videos for this product seemed excessive. It looks like they are working on a less aggressive version, so others must think the same. I like the concept, but I don't think the execution is quite there yet.