Yes, well good luck with that Ebony stuff staying in suspension in big ink carts.
My point was why was a tri-tone set tested for stability and talked about endlessly if everyone is using a 6 channel set?
Whether it is cheap or not is the least of my concerns. I wouldn't dare go around mixing these various brands of pigments like a bathroom chemist and expect them to be stable in the long run. I think it is a bad idea and a good way to damage your large format printer heads. Desktop units are one thing, but big printers are a totally different ballgame.
I do agitate my wide-format Eboni-6 carts, as I did with the third party blended carbon + color B&W inks I've used in wide format printers. I don't suggest this approach for everyone; I find it no big deal for the image stability confidence I receive from using 100% carbon and agitating. For desktop printers, this agitation issue drops out. (By the way, I use a centrifuge to test ink settling. The HP pigments settle less in the open source dilution base than they do in the OEM base. All of the pigments we use settle.)
The 1800 MIS "3-MK" setup was very popular for a while. A printer than can make both a matte color printer as well as the most lightfast B&W made an interesting combination. Many like the black only look. With Eboni MK that approach can make a relatively neutral image on many matte papers. By having the 3 channels of MK, the microbanding problems of a single black only approach were eliminated. For a Shutterbug magazine review of the process see http://www.shutterbug.com/content/new-bw-inkjet-option-using-epson-r800-or-r1800-bw-100-percent-carbon-mis-ink
As a medium format B&W film shooter, I personally liked a smoother printer, which is why I use Eboni-6 as my base carbon image. I assume that Eboni-6 is currently the most widely sold MIS 100% carbon inkset, mostly for the Epson 1400/1430. That printer is what many think is the best and most flexible platform for dedicated B&W printers who want to stay at the 13" level. The Eboni dilutions can be used in virtually any Epson printer, but the user needs to be able to profile B&W, which is rather easy with QTR, both the rip and Create ICC-RGB.
Dedicated B&W lends itself to a rather open source approach to printing. I suspect many of us are former wet darkroom printers who enjoy the more hands-on approach to our medium. We have some excellent materials and workflows available to us to choose from.