Up to now I have used the 6 Eboni inks purchased from MIS. I have made my own QTR profiles using 6 channels: Black, Cyan, Magenta, Yellow, Light Cyan and Light Magenta. The cartridges for Light Black and Light Light Black have remained empty and my profiles make no reference to them. Using 6 inks has worked wonderfully, giving lovely prints.
I just loaded some of the ink I normally use in the Light magenta cartridge, into the Light Black cartridge, ran a cleaning cycle, and printed a QTR Ink Pattern Page. The Light Black channel shows up fine. I will adjust one of my profiles to use the same numbers in LK as previously used in LM and see how that works.
I wonder if sooner or later, another channel will clog.