Sorry, K3 is the common terminology for Epson inks - K, LK and LLK and the others in the set. Whether Pizeography produces visibly better results is really dependent on the image and print size. I have not been able to see any difference between prints made with K3 or Piezography. There are so many variables that one can't state it as fact. It's fact for me, my processing, and images but may not be for you. Now that I know a little more, I would say that the actual print is an important factor in the workflow but image prep and having a good, linear QTR curve, and good softproofing is equally as important. Most images that you see online would make lousy prints. To me, a good print has subtlety but that is not a requirement in the world of shiny screens. Again, that's just my opinion. I made the mistake of going for what I thought was the best method from the outset without knowing what was involved. If I were to start over now, I would use QTR, buy a good spectro, use Richard Boutwell's curve software and look at Piezography if I found that I was disappointed with the results once I knew what I was up to.
As for inks, I have been using P2 selenium and really like it. It works better for me than the neutral set that I started with.