I have had one for 16 months now, and I replaced my old 4800 and before that a 4000, so I have some experience with the type. First off, it uses way less ink than the 4000 and less even than the 4800. Its also very fast, like twice as fast as the 4800. For the first year, I don't think I got a single clog, so in my experience, its been a good printer. I would add than I print on it at least once a week, and in my experience with the 9900, 7900 printers at where I teach, you do need to run them on a regular basis. Sitting there off line is like one of the leading issues to clogging in my experience, you have to use them even if its a test pattern.
It is a big old thing and you will need two people whenever you move it, but I think its a good printer and an improvement over my 4800. I know a lot of people have different views about stands, but I plunked mine on top of my old 4000 stand and it works well enough.