That is the point...which is it???
btw the reps example was years old, was not talking about a current situation. I am not making this up, this is out of the mouth of Epson...Does no one get this?
The previous poster has pointed out where the confusion lies and in fact the mistake of ink swapping in the 4000,4800, and 4880 has been confused many times over the years. The 4000 was a unique printer in the Epson line up, and in fact was the only one that did not require an ink swap. It isn't surprising someone from "epson" was confused, since most likely their knowledge is limited to training, not practical experience. Even some of us experienced in these printers forget about the 4000 and lock in on the 4800 as the one that didn't need swapping. I have seen this mistake (and have actually made it myself several times).
Currently with Epson printers and Black ink switching, there are 3 scenarios. One is a full channel purge, which takes a lot of ink. This includes the 48/78/9880. Second is a head only purge, meaning both MK and PK is supplied to the head but they share the same nozzles. This requires far less ink to switch, and is the method used in the 3800, 3880 as well as the 79/9900. Finally the 11880 is the unique one here, because it doesn't not switch ink. Both MK and PK have a full set of nozzles, and thus requires no switching (0 ink, 0 time), much like the Canon and the HP. In fact the 11880 can lay down both PK and MK in the same pass (such as a nozzle check).
Regarding your original question and support of borderless printing, the US version of the 3800 printer absolutely DOES support 10x12 borderless sheet printing, and I have found no differences in anything of this nature between it and the 3880. I have attached a screen shot to show this is available directly in the driver, no custom paper size needed.
[attachment=21655:10x12_Bo...s_dialog.jpg]