I found a review of the ipf5000 at Red River Paper
. There are a lot of screenshots of the driver pages. The disconcerting thing I picked up from the review was that the dot pattern in the ipf5000 is very visible, especially on resin coated paper and to a lesser extent on matte papers. The samples provided showed that the 4800 had a clear advantage as far as producing a continous tone image.
I don't know if this is a general problem or specific to the reviewer. If it is a general problem, hopefully it can be fixed through tuning of the firmware and drivers by Canon.
If any of the early recipients of the printer have, or have not, experienced this problem I would like to see their comments and samples.