Using the shader in P12 with Powerage RebelEncore hair, Superfly.  HDR lighting although I needed to raise the exposure and denoise in PostFX.  The hair on the left has the shader illustrated above, and the hair on the right was the shader TranslucentBsdf node connected to an AddClosure node instead of a MixClosure node.  To my eyes, the right hair piece appears more translucent than the left.