I have used my 9900 now for almost 4 years and it's been a good printer. I did have a head replacement in year 3, under warranty but that was due to some other issues, non Epson.
However, one issue I see all the time, and really have since day one, is clogs that seem to form after an ink switch.
The vast majority of my work, is done with PK ink, however I will take on canvas jobs where the owner needs a matte canvas, planning to coat it later. I also will put some of my work on matte papers.
So what happened today is a great example and why I feel that one of the greatest weaknesses of the Epson 9900 family is the ink switch.
This morning I started out with 25 large 20 x 30 and 24 x 36 paper prints. The ink was set to PK and before the job I had a perfect Nozzle check, and during the job, 1/2 way I checked again, 100%, at the end of the job, 100%. no fall outs or deflections.
I then switched to matte ink, printer goes through the process of the ink swap, and on completion, before anything was printed, the printer gave the message it had detected clogs. OK, go figure.
I did not turn off the print, print anything, nothing, just ran the ink swap out process, which should move PK, MK and LK or LLK (I can't remember which of these is used in the swap) but now I have the following clogs (breaks in the nozzle pattern)
2 in separate spots in the MK channel, 1 deflection and 1 drop out in LLK, 1 drop out in green, and 1 drop out in LCyan.
Sure, not a show stopper, but you can be assured that on a fine matte paper, these clogs will show up as fine banding, and on a test strip, they did.
Next step, drop into Service mode and run CL1 level cleans on the MK, LLK, Green and Light cyan. After that all clean, and I proceeded to make the matte print run.
But, this is pretty much the same thing that happens to me each time I swap, if not in the PK to MK, then coming back from MK to PK. I personally don't feel that I had dirt or trash on the print head as before I commenced the PK to MK swap, I had a perfect nozzle check. So the question is what happens here? I feel it's something in the pizeo electronics instead of a physical clog as I can't see how a swap would induce a clog. So from my 4 years of use, this part of the Epson Technology is pretty much flawed, may just be my printer, but it's done this from the 1st time I swapped ink. In fact the ink swapping is why I learned to come up in Service mode, as if you let the printer try to clean this, it will take a lot more ink in normal mode and if you try a pairs cleaning in normal mode, you only have 2 levels, medium and high. I can usually get the gaps out with a CL1 level cleaning in service mode, it's just the pain of shutting down, and coming back up in Service mode.
So, I would say, if you are looking at this technology and plan to make use of the MK and PK inks consider Canon's large format or the Epson 11880 which allows you to keep both blacks online. I just don't see it working that well, again at least on my printer.
Paul