Thanks so much for the detailed reply! I'm a bit embarrassed to admit that I've just begun to explore the Digital B&W archives (I mostly dug through the QTR list when I was trying to figure things out), and see that the 5-ink solution and toning was just brought up last month. But it is very useful information, and now I know what to do with the Y position, which will become the cooling tone channel.
Anyway, I'll try out the measurement of the crossovers with the 100% print. I didn't understand that part in your document: I'd measured the limits of each channel on the ink-limited print instead of the 100% print. I'll try it out on the next new paper I profile.
BTW, I live in Santa Barbara, and visited the Los Olivos gallery to see your prints before I decided to try out the Eboni inks. Your prints are beautiful and convincing! (And affordably priced too: they're definitely on my list.)
--Andre