We had this discussion a few months back, but I'll chime in anyway :)

Carrara gives you all the tools you'll need to render great-looking skin. Yes, SSS needs a mapping function, but there's quite a few solutions to achieve the effect. If I think SSS will make an actual difference to any particular image I'm working on, I'll either use Carrara's multi-channel mixer along with an image map to dictate where the SSS shows up on a model, or I'll just shut of SSS entirely and use the translucency channel to create the effect. (It's faster and still gives the illusion of in-scattering)

Like Mark pointed out, different lighting rigs will require different shader set-ups. Global Illumination, Ambient Occlusion, image-based lighting, or just plain old scene lights play an enormous role in the final product!