While the Epson 3800/3880 do not have a roll paper feeder, you can use 17" rolls and cut sheets from this. This will enable you to print larger prints and also panoramics as it will happily accept any user defined sheet size up to 17" by 38".
The biggest problem with roll paper is, as ever, curl. This can be a big problem with the 3880 as it does not have a vacuum sucking system to keep the paper flat during printing, as the bigger models do. This can lead to visible smudges occurring due to head strikes when the paper curls up toward the print head.
The trick is to get it flat enough so that the paper curl is no longer an issue. We have found that roll paper does work okay if you leave it to flatten out by itself under its own weight for at least 5 days. Putting a weight on top does not seem to speed the process up.
We have at times used roll paper to do a quick print, and simply add 20mm to the length of the piece so that any smudge can then be cut off. The printer still spits out the full length of paper even if it is 20 mm longer than the length set in the print driver.