The V4 specular maps look like they are modified bump textures. The darkest areas have about the same value as their bump counterparts but the midtones and highlights (for lack of a better term) are brighter and the image appears to be sharpened.

Since the highlights on the bump and specular maps have similar shape and position, then as you mention they aren't terribly accurate. But into my favorite renderer the addition of that map compliments the bump map nicely when applied to the specular component of a SSS shader. Pores and surface reliefs become visible and tangible elements of the skin.

So any ideas how to bring up the mids and highs while preserving the lows? Thanks in advance.