We have been using Nazdar inks for almost a year since our machine went out of warranty. The savings are almost 50% and the machine runs fine. We have had no colorfastness issues, no nozzle or print head problems, and the chips work fine.
i must say though, we are very anal about keeping our machine clean, running a nozzle check and a head blowout at the start of every day. Its been a little over two years and a move (not by an HP tech either; we used a flatbed wrecker) and its running like it was new out of the crate.