Whats really nice about this shader is that it has 2 rather intuitive material parameters that you can use to further control the hair highlights. I really wish I have the slider UI implemented so I can show a gif, but alas, I don't atm. So here are some pictures instead.
The first parameter is Smoothness (or Roughness known in other engines/modelers) that controls the oversize size of the highlight:
Really large and unfocused highlight:
Smalled and more focused highlight:
The second parameter is "Metalness," which controls the ratio of specular highlight versus diffuse:
The second feature added is SSAO! You might not noticed it, but it's there for all the pictures above. Here is the first picture without SSAO:
Here is the "after" for comparison:
This uses a new and improved implementation compared to what HR and HRT had. One of the more noticeable effects is mitigation against the "halo" effect:
*These 2 pictures are taken with a stronger SSAO effect to highlight the halo. The outlines are from a separate effect, not from SSAO.