A few points.  First, GC is an approximation, and it's very noticeably off by my eyes as soon as you get to darks.  Dark by cast shadow, dark by shading, or dark by color.  Doesn't matter.  It's why I kept posting about sRGB correction being better than GC correction in certain situations.  You get down to 10 to 1% luminosity on lights, and GC is almost glowingly bright before it goes pure black.  Render GC also messes up a lot of key calculations. Render GC affects Blender and Color_Math behavior at the very least, and probably several other types of nodes.  Neither is a huge deal most of the time, but for full dynamic range in extreme lighting conditions like you're using as your test, something to keep in mind.  On Blinn, I'm not sure if it's clear, but Blinn has Fresnel built into it already.  The Eccentricity is a sort of inverse Fresnel measure (how strong is the Fresnel effect).  If you use it with another Fresnel node, you're doubling down. 

But most important of all, it reminds me of the shading in NASA photos that aren't broadly lit by earth.  I think that's how something with no internal or external scattering is supposed to shade.  I'm pretty sure you're not supposed to get soft shading in a perfect, black vacuum with one light.  Poser definitely has some GI shortcomings,  so IDL doesn't soften shadows or shading quite like more accurate renderers do.  But that's not a GC issue. 

If you're focusing on people, then there's a big problem with treating the flesh like it's all one substance.  Shading in people is a combination of dermal and subdermal scattering in addition to diffuse, reflective, etc.  Subdermal is pretty short and deep, but dermal is very shallow yet broad along the surface.  So dermal can really soften the shading along the surface, which is the kind of shading you seem to be concerned with.  Trying to combine the two into one subsurface scattering phenomena means you get skin that's way too translucent in terms of seeing into the volume yet has too sharp of a terminator in terms of shading.