I want to say something intelligent on this point, but I'm not sure I know how. Anyway, sometimes the most intelligent thing to say is rather on the stupid side, in that it might stir up more intelligent answers.

I don't know, for example, what the visible channel or the UV channel are measuring. I ass-u-me that the RGB channels are measuring something related to color separation positives for dye separation or similar processes. Do the specs for a commercially available densitometer provide spectral distribution plots of what these channels measure? If so, what does the visible channel have to do with photosensitive materials, when panchromatic films are more sensitive to red and blue than the eye? How much of the UV that is measured will get through the glass of a printing frame?