Stephen,I haven't used my 800 in a while. Great printer. What paper and profiles are you using?
I've only been using the Epson software, I've not added any special profiles, something of a grey area in my understanding. Doubtless I could refine my results by investigating that subject further. I tend to use an Epson heavyweight glossy paper in the R800, set for best photo (2880 dpi perhaps?, my old 790 used to treat you as intelligent and give you such information, now when you select "advanced settings" you're confronted with a dialog screen that basically patronises you and tells you this is for advanced users). High speed off, gloss optimiser on, greyscale on. As a straight print there is an obvious colour cast, I am slightly blue/green colour blind (I'm told about 10% of males are) so whilst it's obvious I'm never very sure just what is making up the cast. I hit on a setting of -10 for both magenta and cyan with a very definite improvement. I think it might still be work in progress as I should really wait until daylight tomorrow to fully judge the result and then perhaps try further, though probably much smaller tweaks to the settings if needed.
Again my old 790 allowed you to select black ink only, 2880 dpi and gloss paper, producing what were to my eye excellent b/w prints. I recall downloading several articles on the subject, written I think for the 1290, which was really just an A3 version of the 790. More up to date printers tend to deny you this type of full control.
If you have any thoughts on profiles I'd be glad to hear them.