I don't think so, other than the color materials seem to generally reach a higher max density.I think the difference may come purely from the original preferred print studies being black and white and Giorgianni's study is color.
(Update: amended per my following post #65; I acknowledge that skin tones in a color print are not allowed to get as light as B&W can, because the color will be lost as paper-base white is approached. So, except for specular highlights, fleshtones should not be allowed to go light enough to have washed out color.)
On your (4th Quad) graph, the added (red) reference line looks good - it now serves as a legitimate "original scene" density reference. My only problem now is that your tonal curve does NOT allow for specular reflection. It ends (lower right) at zero on the "Reflectance" scale, which I take as "equivalent density" of zero in the original scene, that is, 100% (diffuse) reflectance.
In the original Giorgianni chart, you can see that the lower right (the highlight areas) extends about 0.30 log exposure units beyond "pure white" (which is "0" on the "Log scene luminance factor"). This allows about 1 f-stop equivalent of highlight detail to be reproduced, in a compressed manner, on the print.
This ability to reproduce a nominal f-stop of specular reflection is the only (significant) difference remaining between the two graphs. Yes, there is some difference in the shape of the curves, but there is room for artistic intent there.
FWIW, I have some experience in building tonal curves for use in portraiture. I found that I had to closely mimic the lower portion of the Giorgianni chart (the transition from specular reflections until meetup with the reference line) in order to handle both specular skin reflections and the slight folds and texture of a white dress shirt. I did a lot of fine tuning, but there is not much leeway for variation. Other subjects, such as landscape scenes, may find modification of this curve to work better, perhaps as in Stephen's graph (with some specular highlights built in). I can't say for sure.