Great, Thanks Doug.
I'll look forward to profiling the paper(s), and seeing how this changes things in the prints, if at all.
Very interesting to see the improved response, for the large part, from 9800 to 10000/20000 range. It is not that surprising given almost a decade of progress, and 4 grays in the inkset, but, logic does not always follow through! As you point out it is not a perfect response, and it would be interesting to know if the Canon's are any better in this regard or not - but that's for another thread, another time.
How would those wobbles around the lower end of a* and b* manifest in printed images? - I do see flesh tones of people in shadows having some strange shifts, mostly to red, that need a curve and mask to correct, but that may be the IQ100 response, (which is not a Trichromatic) rather than the profile. We'll see.
Sadly I'm away for the next 6 days, but will report back in a week or so, once profiles are built and applied to a variety of images.
Thanks again for your help with this - are you a color management professional, a math nerd, or simply a very numerate amateur?!