Hello Ernst and Alan,
thanks for the comment.
I agree with both of you:
in fact I currently have settled my working spaces to AdobeRGB and Gray Gamma 2.2 colorspaces, which share the same gamma companding function.
Frankly said, I use AdobeRGB even for color, but this is not the right place to start another ProPhoto vs AdobeRGB discussions. The argument is well documented elsewhere and all the advantages/disadvantages are known, so it's good that everyone can make their own choice based on their specific personal requirements.
The project started as B&W optimized, as explained,
but after some test I realized that, as ICC print, the L* linearized tone curve could be tested/used even for color prints without fear of massive undesired side effects, being equivalent in theory to a common adjustment of the L* channel in Lab mode.
The use of the tone neutralized correction in color prints raises more question in my mind, because I cannot be sure that a color shift correction based on the gray axis could not bring unwanted color shifts in other gamut zones. So, this specific case is currently something to be considered "experimental" and under test.
In any case, for potential color applications/test I think that it could be useful to have still ProPhoto covered.
Any comment is still welcome.