I have not spent a ton of time using ABW. But I did make some curves for QTR that only use the K, LK and LLK inks. I did not really care for the color of them and accepted that I need some M and C to make them pleasing to my eye. You may want to test that out with QTR to see if you like the look of the black only prints before you spend a ton of time in ABW trying to get there.
If you have a flatbed scanner or a macro lens you can easily image the dots to see exactly what's printing. A scan at 2400ppi works well.
With QTR to get a warm tone (matching old Forte Poly Warmtone) on the 7900 I didn't use any yellow ink. I would hope ABW isn't adding yellow unless you try for a warmer tone than the black inks. If it is I would definitely switch over to QTR since the yellow inks are the least stable.
Larry