I also apologise for quoting 5.5.5 etc for highlight values. I think I must have got caught up in Eleanors "whoops'. As no one rebuked me I guess everyone knew what I meant.
Despite a bit of a biff on out the back this has been a useful thread and I thought I might add what may be a couple of useful observations.
I have just been testing the Pictorico high gloss film , the so called "digital Cibachrome". It was not quite as glossy as that description infers, but it is ultrasmooth. The gloss differential though, using K3 Photo Black, was minimal. In fact you really have to look for it by flexing paper (or, should I say plastic) this way and that against a specular light source. Incidently a very neutral greyscale resulted on this product using the Epson Gloss canned profile and the Epson Gloss driver.
The second observation picks up the dreaded Matte Black/ Photoblack problem. My 9800 usually has Photo Black in as a default. I still have a 4000 (I hear you Mark, I hear you) and if prints are A2 or smaller I can print with matte black there. Yesterday I was printing on BreathingColor Stirling, which is a smooth matte paper, on the 4000. I particularly wanted to use Matte Black as this particular set of images required dense blacks to be successful. When the printer started to give 3 cm wide soft banding, which cleaning did not rectify, the client being with me, I had to move rapidly to the 9800 with the Photo Black ink. The first test showed lousy blacks. I shifted from the custom Stirling profile to canned Epson Watercolor Radiant White (don't ask, just a hunch provoked by terror), set media as Enhanced Matte and nominal resolution to 2880. The black was visually great. Even in bright sunlight. I had to tweak the low end of the curves to open up a little deep shadow detail.
I have not measured this black. The approach may not work with other papers or even images.
All the same I had a very happy client , and am not feeling quite as aggravated about the PK/MK problem.
Oh yes; I think a wasp may have set up home in the 4000. B****r