...Although I'd gotten used to the warmish black of diluted Eboni,...I'd welcome a cooler option, it adds to the repertoire.
I totally agree.
Won't the blue lessen the archival qualities of a strictly diluted Eboni approach?
Yes, but with a relatively neutral carbon and the best pigments, the amount ought to be small. The color pigments only account for about 5% of the density of a neutral print with my approach. Some of the blended "neutral" inks have huge amounts of color pigments in them.
Although I wish there were a perfect single blue pigment that would do the job, such is not available to us. The second best situation is the cyan that is closest to blue (Epson among those I've tested) and a blue pigment instead of magenta. Canon has one that is available in large carts. By keeping the cooling pigments as close to the ideal blue that offsets the carbon yellow, it takes less color in the mix. The less color and higher percentage of carbon, the better in terms of longevity. "Carbon is king" with our current B&W printing technology.
The problem is not only the Lab L fade. The harder issue is the tendency to swing into greenish as the color pigments fade deferentially. The cyan is usually stronger than the magenta that is used to offset the carbon. As best I can tell from the AaI&A tests, the Canon Lucia EX blue is our best bet in terms of finding a pigment that can stand up to the cyan. There is a detectable Lab A reduction in the neutral test strips, but it's very small and expected. It may also be from the individual pigments having a bias to have some Lab A fade. How far it will go remains to be seen. The information I could glean from AaI&A is limited by, among other things, the test patches that were used not being such that the pure cyan and pure blue would be the only inks used. I took my best shot with the current toner, but the general approach is open to changes and improvements. If Mark's tests of the new P600 pigs shows they are a quantum leap (not likely, I think Canon already implemented the next generation coating with the EX version of Lucia), I'll test a version of a toner made from them.
I appreciate the contributions you've made in submitting samples to Mark as well as trying to make scanner based linearization more accessible to people. If people can just linearize a profile -- QTR or ICC -- it opens up a lot of printing flexibility and power to them.
Paul