Hey @jandren! Nice to hear that you are interested in this.
I can add a couple of plots that might start a discussion, or at least trigger some thinking.
Online sometimes you can find LUT tested against “stress test images”. For sRGB inputs often this one is used (3dlutcreator link):
I don’t like it too much because it is not very smooth from the beginning. But let’s have a look.
Taking only the left square (only a few columns of the image actually) and plotting it in a chromaticity plot gives the following.
All the extreme values of sRGB are reached. The lower part of the stress test image runs over the edge of the gamut, while the top part desaturates and goes towards D65 white.
I was curious to see how the chromaticity plot would be mapped after the simulation. The stress test image is not scene referred, so the print will be quite dark (small latitude), but might still give some insight.
This is using high saturation Kodak Gold and Endura Premier paper.
This is using low saturation Portra film and paper.
I note that shadows now desaturate towards black, and curves from white to black are mostly smooth, with some funky twists (the curves are coming from the columns of the stress test image). Also the gamut stretches outside sRGB, especially on the blue green side.