I have 2 Epson r2400 printers at work, they have been a source of frustration for me over the past 12 months, to put it simply they didn't work that well with OSX. I read every article I could find, and methodically tried every combination of print option, but the best I could do was manually set the gamma, brightness and saturation to produce an approximate result. Prints always had inaccurate blacks and were masked by an overlay of grey. I mainly print out of Adobe CS3 and none of the packages produced consistent results.
Finally a real solution has arrived! Adobe has released updated drivers for the r2400 so if you are still having probs with your R2400 and OSX then head over to Epson's site and get the latest drivers, they are dated from August 2008 onwards.
As a side note to Epson while they make great printers their Mac drivers have been awful since moving to OSX and that is a fair while ago now. I have recently bought a cheap Canon A4 printer for general printing at home and it has a much more reliable set of drivers than any Epson driver I have seen in recent years. Looks like its time to say goodbye to Epson for a while. After waiting over twelve months for a proper solution for OSX printing I would have to recommend users look very carefully at the functionality of any printer they ar considering buying, with their specific Software/OS combo before making a purchase. But at the end of the day the problem really boils down to poor development and user support on Epson's part.
The big lesson from this: If a printer is critical to your workflow then find a store that will let you try one out with your system, before you purchase or a store that has specialist industry knowledge about printing photos and graphics.