We run three 4900 printers. Because of our work flow it is imperative that all three printers print identically. The largest percentage of paper run on the 4900's is Epson glossy photo paper SO41271. Everything discussed in this thread has been run on that paper. Last fall, after running test prints from your supplied files and comparing those to your sample print created with your CC HDR inks, we decided to give Cone Color inks a try.
We started by converting over one printer. While information indicated that the inks were close enough that we could switch on the fly I did notice while running 100 prints of the same file and having switched out the blacks that there was a definite gain in red and loss of density. Nest step, get the full set of inks in and install the Cone Color profiles. Having done that we ran tests ofr your control image along with a 24 step gray scale. Using the CCP-4900-EPptoPaperGlossy profile and setting the media type to Ultra Premium Photo paper Luster, as outlined in your info, rendered a test print that is very red in the blacks compared to the same print on a 4900 running Epson Inks, and the Epson ICC profile and media settings for that paper. Interestingly a print on the Cone Color inks using the same Epson profile and Epson glossy paper media type renders a print that while still decidedly red is closer than the one created with the CCP-4900-EPptoPaperGlossy profile. While it is generally possible to correct for the reds, there are occasions when we just cannot reproduce a color as accurately as we can with the Epson inks. Until we get the CC inks printing to match the Epson inks I do not want to switch over my last machine.
It may be time for the custom profile, however the fact that we are farther off with your supplied CC profile than the standard Epson Profile makes me wonder if I am missing something.