Well, the edge (/teeth) on the back of this very special karambit is perfect for cutting your own thumb unintentionally.As I stated before, the profile is a very traditional one. It is very similar to the HS designed by Steve Tarani.
The HS has a 8cm blade, the CS has a 12cm blade, so I'd prefer the last one. It's not illegal to sharpen the back of the CS karambit, too. I wouldn't sharpen the whole back though.