The problem with the old skin shaders is that the creators continue using old hacks and outdated channel connections that are no longer appropriate for Superfly or Firefly  rendering.  Aside from unticking the Reflection_Lite_mult box, I would try disconnecting the Gradient_Bump channel or reducing its value to 1 or lower.

The other recommendations I suggest are disconnecting the color texture from the Specular_Color connector (should use a grayscale map for that) and reducing both the Diffuse_Value and Specular_Value values (0.85 and 0.5, respectively).

Keep in mind, some of those material shaders are very old and are no longer valid in the current Poser iteration.  There have been changes between P12 and P13 to correct problems that were always there since the beginning.