2019-01-14 by john.isner@...
I have a P400 and am quite happy with it. I use it to print PiezoDN digital negatives, and have printed several hundred, from 8.5x11's to 11x17's, without any problems. My only complaint is the frequency with which you'll need to refill cartridges. Digital negatives use a lot of ink. I can print maybe a dozen 8.5x11's when the printer tells me the ink is getting low. But as someone else in this discussion said, you'll have fewer problems with the desktop printers, with cartridges that sit directly on the print head, than you'll have with 'pro' printers with large stationary ink tanks.
Inkjetmall has an inexpensive chip resetter for the P400, so you will not have trouble using their cartridges unless Epson has changed the firmware since I purchased mine. I don't know how you'd check this before you buy. But once you do buy, be sure that you don't accept any firmware updates. An update might invalidate the use of third party cartridges. This warning applies to all Epson printers, not just the P400.