I've been using RIHAC inks (100ml bottles of each colour) for a number of years with my Canon IP5000, IP4000 & IP3000. I kept these printers as long as possible because they were unchipped. When these printers eventually failed, I got a IP4600. Since it's chipped, I feed it with a RIHAC CISS which comes with chips. I'm half-way through the first tankfull (100ml per colour). No problems. It's great to be able to print out an A4 photo without worrying about the cost of the ink used.
RIHAC Digital Solutions
The only negative I've seen is it makes the printer nosier, because the top lid does not fit flush anymore because you have to allow space for the ink tubes. I could improve this with a mini-grinder, but I haven't bothered yet.
Dan.