I've been running EternaChrome bulk inks in the Epson 2100 and been happily printing on matte paper using the the MK (matte black) ink. I recently changed over to PK (photo black) ink to print on glossy papers. Specifically, I wanted to use Ilford Galerie Smooth Pearl (old version) and Smooth High Gloss for some exhibition prints. I was rather perturbed by extremely muddy and blurry results in the darker areas.
After a lot of trial and error (mostly error), I established that the EternaChrome inks were simply not playing well with these papers, the ink pattern being laid down was coalescing leading to blotchy results. The only way to reduce the coalescence to acceptable levels was to switch the media settings from the recommended Semi-Gloss to Watercolour Radiant White which restricts the print resolution to 1440dpi, but even this required a -15% ink density and reduced Dmax. Unfortunately, the 1440dpi mode results in visible banding in the darker areas and so is not suitable for exhibition prints.
After more trial and error, I have given up trying to use EternaChrome with these papers. In comparison, I have successfully used EternaChrome with the new version of Ilford Galerie Smooth Pearl (HDR), Epson Premium Semi-Gloss, as well as generic satin paper from 7DayShop. My conclusion is to avoid using the old version of Ilford Galerie Smooth Pearl as well as Smooth High Gloss with EternaChrome.