Mh, i've been using PM a lot recently because one of my computers doesn't have IDraw, and i've come to the conclusion that it is not simply nostalgia that keeps me using it. Even now that I'm used to PM, Idraw is just so much more comfortable. Mostly comes back to the fact that snapping and selections are clumsy in PM and intuitive in IDraw, and I never use the additional file formats offered by PM. Everything else (palette, drawing) is pretty much the same.
The saturation exercise would seem interesting. CMY get the big brightness boosts I should think, they have the most color for what's produced. Dunno what would happen to the others.