Digital BW, The Print

OK, I've kicked off the process of making some curves for UT2 inks 
with Hahnemuehle Fineart Pearl paper, starting with the Premier Semi 
Gloss curves on Paul's website. First thing - print a stepwedge, have 
a look at it and examine the curves in photoshop.

The neutral curve looked pretty neutral, the steps between 95% and 
70% looking a bit light as best I could judge by comparison to my 
monitor. I know I could simply do a 'create ICC' at this point and 
have done with it, but I want to understand...

So I take a look at the curves. I've read Dirk Hobman's explanation 
of how to interpret these from the MIS website. I'm rather surprised 
by two things. First, the neutral curves for Eboni ink have a blue 
curve that is almost flat across the top of the grid. My 
interpretation of this is that the light grey doesn't get used with 
this curve. Second, the version of the curves for Photo Black has the 
blue curve dropping to zero at the left-hand end of the grid.

From Dirk's explanation, I understood that 'all inks at zero' was 
needed so the Epson driver would know to get the black ink working... 
so where does that leave the Eboni curves? Is the light grey more or 
less redundant? And what tells the driver to bring in the black?

This is giving me a headache!

Any help appreciated,
Ben