When I re-watched the Version 8 webinar, I remembered a suggestion I already made in "Daily Builds". In the Curvature shader presentation it pretty much boilt down to "and this shader is used as a mask for ...".
So here's my request again: Add two outports that provide us with a mask for concave and one for convex. It saves us from having to change the colors to black and white. Keep the original output, of course, it is useful in some cases. But the masks are needed a lot more often.