I use a 9880 for photos on canvas, but also to make prints of my wife's pastels. Works very on all counts, the pastel prints are very accurate on both matte art papers and even canvas. Under glass it is almost impossible to tell a print from an original, we have to be meticulous about labeling prints as such.
The real trick is to get good image files of the originals. I shoot usually shoot 4 to 6 shot stitches of the original art outdoors around mid morning or mid afternoon with the sun at 45 degrees to the print. The result is a file around 50 megapixels that prints at a few hundred camera pixels per inch on the print, even big prints. 105mm lens to minimize keystone. In Photoshop I straighten out any remaining keystone with Free Transform.
I use a taped up lens hood with the minimum possible opening, this prevents flare in the lens. I need to do that because the art receives bounce light from nearby (neutral colored) concrete which is bright enough to flare the lens. Make sure your print doesn't get bounce light from colored objects. For whatever reason shooting art in outdoor light never worked well with slide film, but I think it is preferable to flash or tungsten for digital.
If you are new to stitching, the free MicrosoftICE program does an outstanding job with very little learning curve, but if you want to maintain 16 bit color you should use something like PTGui or AutoPano etc. But 8 bit color is really OK for art because you make almost no adjustments in post processing.
But I'm talking about 30 x 40 art here, for prints up to about 18 x 24 a single 10 or 12mp shot would be adequate, no stitching needed for that size.
I'm sure you know the 4880 can only contain a matte black or photo black cartridge at any time, and that there's an ink-wasting penalty for changing between the two. You would use matte black cartridge for watercolor and other matte papers.
Edit...also, I believe the Pro model comes with RIP software. In the case of Watercolor paper, you probably would be better off spending the extra money for the Pro version for a good calibration puck which will allow you to make you own printer profiles well tuned to your particular manufacturing sample of the printer. There is already a watercolor media setting available in the Epson printer driver, that sets among other things the general way the ink will be put down. The printer profile fine tunes this. Kinda sorta, that's the jist of it anyway. The RIP would be of more use if you were trying to use unusual media, but for the commonly available printing papers wouldn't have much to offer other than ganged-up printing.
