I installed a CIS/CFS in my last printer, an Epson 1280. I don't do a lot of print volume, but the economics are hard to beat. That having been said, I doubt I'll put up with another any time soon with the new Pro9000.
These CIS/CFS kits more often than not are half-assed hacks. On the Epson, it was clear that it wasn't implemented well at all. I had to use two good-sized erasers to prop up the hood which would no longer close properly. The yellow tank leaked from day one, the replacement tank was different than the others and I had to hack it to work and even the replacement soon started leaking - even more than the first one! Getting the carts primed was a ****. Finally, the inks didn't match the Epson inks close enough and having a hard time getting a decent matching (WYSIWYG) print to start with - didn't make it any easier. In fact, I don't recall getting one freakin' print to come out right on that printer... Ever. Don't even get me started on the almost daily head clogs and other problems with that printer. UGH.
I got the Pro9000 so I could once again have a simple, reliable printer - that matched what I saw on-screen. Score - on all points. I'm not going to mess that up with a CIS.
Just my experience...