You guys are awesome, thank you so much for the informative replies.
How'd I forget about the HP printers? Duly noted that the 3100 is better for black and white. Does it make a difference that the "tone" I prefer in my black and whites is more reminiscent of a pencil portrait? A little cooler, not as warm I guess...
If you only want to print black-and-white, you want either MIS Eboni or Piezography. No colour inkset can even come close in terms of tonal range, detail and longevity.
I'd suggest the pure carbon options - the MIS EB6 inkset or Piezography Carbon. These use exactly the same pigment as found in a pencil portrait - pure carbon/graphite - and will never fade. You can display them in direct sunlight, or even outdoors (as long as they're protected from wind, rain, etc.). There are other non-pure-carbon inksets within the MIS and Piezography lineups, but these have a tendency to fade towards a nasty green hue, sometimes relatively quickly.
EB6 is more-or-less neutral, with a slight hint of warmth - very similar in tone to pencil on drawing paper. How warm or cool it appears depends mostly on what paper you use. Piezography Carbon is warmer - perhaps a third of the way between true neutral and a sepia-toned print - but can print on glossy paper.
That said, if you must stick to an OEM solution, black-and-white output using HP's ABW mode is better than that of Epson or Canon. But it won't be nearly as good as a dedicated black-and-white system and will be more expensive to set up (since you can run MIS/Piezography using older printers just as well as newer models) and to run (cheaper ink).
