Hi Dave, I hadn't answered because I have no first hand experience of CIS's.
I have however read several user reviews of the systems and all seem to say that they work well and everyone is happy with them. however there is a lot of warnings to steer clear of the cheaper ones as they can block and dry up. (the cheaper ones seem to use sponges which can dry out)
also every review I have seen on them has warned that the install process is a little fiddly and very messy! (and trust me printer ink takes ages to get of your hands!)