Another FWIW comment... as far as I can tell (seeing what is published on the web, talking with people in person and long personal experience, your comment about the prevalence of Epson printers for making digital negatives still holds.
I am unsure why this is. However, I suspect that this is because the Epson K3 ink set is known to have adequate density in the UV which is, of course important for alt process printing. This, is probably less of an issue for silver gelatin printing.
If I was going to buy a non-Epson printer for digital negatives, I would ask a dealer to print out a simple step table using the printer I was considering (or at the very least a printer using the same ink set) on transparency material. I would then print that step table using my process of choice. You are not looking for linearity at this point... just that the ink(s) can make a negative that is dense enough.
More likely, I would just buy another Epson printer!
(Note: I am mainly an alt process printer.)
One additional thought... will the printer you are considering print on transparent medium without resorting to a work around (e.g. tape on the leading edge or the need for a carrier sheet)? Having to use a work around could get pretty tiresome if you make a lot of digital negatives.