I agree. I always said, and I'm sure was not the only one, that CoC coating it's just a surplus when we already have CoA. If I were Oda I would have expanded the "aura" aspect of CoC, the one that makes you faint. Maybe he will, we know that there is also the "observation killer" side of things. But for now, seems like that using CoC with attacks it's just like attacking with a stronger CoA attack that can also damage the ones with regeneration.
It's like there is no big difference in coating an attack with CoA or CoC, it's just that the latter is a more powerful attack. There is no peculiarity in CoC coating.
But even that, Sanji sure deserves it.