Close
I'm also troubling filtering on the darks. I ended up keeping colors, and became using tone curves before/after filtering instead. even though, I couldn't keep contrast among edges/surface in the dark. still working on progress.
(blacking out the value of edges can avoid filtering, but I don't like this method :/)

to aoie: greyc, neatimage, surfaceblur, sgblur, warpsharp. and using them with masks (I'll write it later) :P