QTR-Quadtone RIP

I'm going to post in both QTR and Piezography 3000 forums in the hopes that someone can help me out.

I recently made a concerted effort to get back into b&w printing on a desktop inkjet.  I decided to go with the Jon Cone K6 inkset for my Epson 1280 printer.

I am not using a continuous feed system.  I went that route with b&w printing a few years ago and my printing needs are infrequent enough that it just doesn't make sense (maintenance or cost-wise).  Instead I am using spongeless cartridges from MIS.

In prepping for this move I bought and installed a brand new print head as the old print head had two nozzles that just would not unclog after all sorts of cleaning.  Nozzle checks with the new print head were perfect using Epson OEM inks and with Cone flush ink.

Loading up the new K6 inks also went perfectly.  Beautiful prints.  But I was only able to get about 10 prints out before I had missing nozzle checks.  Several cleaning cycles did not fix the problem.

I thought maybe the cartridges were defective in some way so I loaded up a new blank set of cartridges.  After installation, bingo, first time delivered perfect nozzle checks.  Printed about 5-10 more prints before same nozzle clogging problems occurred.

Cleaning would not solve the problem.  I put back in the Cone flush cartridges.  Beautiful.  Perfect nozzle checks.  Put back in the K6 inks.  No joy.  No amount of cleaning gives me a clean nozzle check.

I'm close to giving up on this system but I know there are many out there happily printing b&w.  So any hints on what to do with my system would be greatly appreciated.

I know the 1280 is outdated and I have heard that nozzle clogging can be an issue with this printer.  I thought the pigment in the K6 inks were supposed to be the finest particles yet from Cone.

Do I...

1. Perservere with my 1280 and Cone inks?  Anyone have some hints?
2. Give up on the K6 inks and move to MIS inks?
3. Give up on the 1280?  The Epson 1400 uses the K6 inks too.
4. Switch both to the 1400 printer and to MIS inks.
5. Give up on these 3rd party b&w inks altogether?  (I hope not)

Regards, and thanks in advance.
Mike