One suggestion I made to BM during beta testing was to bold the tabs that had been used – I agree that right now, trying to figure out which curves are used on which node is a bit of a pain.
But I’m still not convinced of a need for a paradigm shift. In many cases the node thumbnail reveals a lot of information about key/window that’s on it. With some labels, and maybe even the popup overview you mentioned, revisiting a grade is easy enough.
I’m still not quite sure what about layers vs nodes makes it more intuitive. But you’ll have to forgive me – I’ve not worked with a layer based coloring software.