Thanks to you all for your helpful answers.

@Toxicwolf: I've realised it looks alright once rendered although a little shine sometimes subsists on the render. I don't know much about shaders, i must say it's rather hard to understand how it works.

I have 2 characters, one "normal" one shiny, both look fantastic (i don't know if I can mention the vendors)

Rendering of the shiny one takes much much longer (I'd say 4 to 6 times) even on PP2010, so without using the SSS.

Why is that so?