Peter,
I've just been knocked on the floor. What you said about your R290 did not surprise me because I kind of expected that it was close to one of the other Rxxx printers.
However what you said, plus my frustration with not being able to find a listed printer for sale, made me throw my hands up in the air and "play" with QTR and my Epson TX810FW. I tried the R390 selection and I just got garbage and many sheets of paper feeding out. Next tried the R800 selection, put the black settings at 100% and pressed print. The printing took a very long time and when the paper finally came out I had to catch it to stop the FLOWING ink from pouring off. Put settings down to 50% and reduced resolution right down just to test and I got a perfect print.
I've been to hell and back with 2nd hand printers, spent at least $200 on them, none of which have been fully functional, and put a lot of time into attempting to resurrect them, only to now find I can print with unlimited density from my all in one printer sitting on my desk.
My guess is there may be quite a few other Epson printers will work like this with one of the driver selections. Maybe no good for black and white photo printing but good for making film positives where only the black is needed.