If anyone finds themselves in a similar position, look to see if QuadTone RIP is showing up in the Epson dialogue box, if it is and you have legacy QuadTone software make sure to remove it (there's an uninstall package on QuadTone's site). This fixed it for me. Or at least nearly fixed it, I'm stil left with the "dark B&W printing" problem, but that seems pretty well documented elsewhere.