Here's a Before/After comparison. (Click to enlarge)

Image 1: VSS 2 prop with VSS 3 mat file applied, full scene gamma correction and saturation boost from Bagginsbill's Artistic Lens

Image 2: Mud shader, no VSS, full scene gamma correction and saturation boost from Bagginsbill's Artistic Lens

I ended the rendering process early because the hair and dynamic fur were taking forever (a few hours) because I accidentally set the Render Settings too high. You might notice that the hair and stomach are considerably less grainy in the second image, probably because I set the irradiance caching, pixel samples and render dimensions way up for a small test render and forgot to change them back. The resulting image was 1280x2133 at near max quality. It's VERY sharp, but actually looks worse in some ways because the skin did not have Bagginsbill's VSS applied to it.

I didn't apply the mud shader to the gun because it had WAY too many parts to apply it to (about as many as V4 and the other props combined). It looks like I missed applying a texture to the shorts in the first image though. Also, I may not have applied the mud shader to the hair correctly, because I can't hardly see it. It may have to do with my copying of a transparency node from the original mat settings because the mud shader removed it. I figured it was important to keep it, but it may not do what I think it does.

And as I should have known (had I given it any thought), the mud shader is completely obscured on the boots by the dynamic fur. So different footwear will need to be used in renders where mud is required.