In 8, though, when I turned the bump node to tangent normals it didn't change anything at all, no matter what strength I set it at. Setting the bump node to bump does affect the surface, so the node and shader and all seem to be connected right. Is there some option I have to check to get the bump node to work set to tangent space normals?
Using the normal map just as a normal map works (using Pixero's JSNormalMapper), but it doesn't work as well for simply increasing the strength of lower level noise.
Here's some pics:
Just displacement map
Normal map as normal map
Normal map as bump