A couple of things I still need to check:
The fix in (1) includes the alpha in the normals, I’m not sure if it should. Likewise, right now it uses a rather narrow comparison (0.99) to determine if all the normals are pointing the same way, but textures with bumpmaps might justify reducing the 0.99 value to ignore surfaces that are mostly flat. I’ll also put a note in the shader itself about how high ambient lighting washes out the red facial shadows.
Also, if you change the line color from a constant black color to the output of the add that goes into Lerp A multiplied by 0.4 or so, the outlines will be darker versions of the color of the material instead of black.