I haven't seen Chris Korn's Coppa Silva (yet) but it seems very similar to Geoff Latta's Fisting C/S (orig pub'd in Richard's Alamanac). Anyone here familiar with both effects that can give me some insight?

They are indeed very similar. Without exposing methods it's not possible to describe those differences in detail. As I recall, the method of causing the transformation (stealing the "something" that makes it work) is the main point at which they differ.

I doubt a layperson seeing both would be able to tell you any difference.