As good as that skin might look, Marmoset is a renderer, not a game engine, and doesn’t have all that extra overhead.
It is fully possible to use your own custom lighting models in UE4. Just select subsurface and plug your “node-code” into emissive. There were some good implementations in UE3, some of them hideously expensive though (like that D3D shader or whatever it was that used 6 blurred normal maps).
Epic did also state during the Rendering Twitch Stream that they are working on the skin shader.