John,
I bought some 4x6 sheets of the Canon Plus Glossy II paper. The first picture I printed was a nature shot I have been using as my standard. Surprisingly the bright green came out more brownish than the HP or Epson papers! The detail looked better however giving me a sharper image where fine detail was present.
Then I printed out a picture of the graded paint color samples I got (took this picture in good sunlight). Some colors weren't too bad like purple, blue and red getting the right shade but the printer didn't get as dark as it should or with the lighter shades it was always darker. So the intermediate intensities matched fairly well. Where it deviated from the original colors was in the browns, yellows and most notably greens.
The MX922 does not have a way to manually adjust different colors like you show above for the Pixma Pro 100. This is exactly what I have been inquiring about. I don't think you have room to play with the MX922 especially since the Glossy II paper is one you can pick from the menu. I would not be surprised if the Pixma Pro-100 offers better color matching, particularly for the lighter tones since the extra inks favor lighter intensities.
So are we coming to the conclusion that the Pro100 offers better versatility for color matching? Otherwise I will be fighting a challenge to get authentic green tones in my pictures - something a wildlife photographer needs to have. The way I see it the MX922 is intended for general home/office use. We probably shouldn't expect it to perform at the same level as a photographic printer.