Wayne: minor for a single swap, sure - but cumulatively? Eric Chan in his 3800 Wiki estimates $3.00US/CDN for a switch from one black to the other and back.
You are right ... if you are constantly swapping blacks this is more problematic. But still far less than the bigger printers, and it still seems logical from an engineering perspective to get a 3880 printer to market you most likely wouldn't re-engineer the machine because of the ink swap. This would involve a complete new head. It would be a nice add, so maybe Epson will surprise us.
It is a bigger deal on the 48/78/9880 printers, and I hope Michael's guess is right about a photokina announcement to put the 11880 head into these smaller printers. That would be a significant upgrade .. higher quality, clog problems pretty well gone, almost twice as fast as the previous printers. That head is so expensive it begs the question whether they can actually put it in an affordable smaller printer ... they may end up with a new line of "high" end printers and charge a little premium over the cost of the current printers, leaving the current printers also available. Fun to speculate
I'm so enthralled with the quality of the new fiber/baryta papers and their look that I'm inclined to agree with Michael ... just as Epson appears they are attempting to address the ink swap issue, I may find I won't be using matte black anymore anyway. I have an 11880, and haven't used MK for several weeks. Maybe the love affair with Epson Exhibition Fiber will end when I get the bill from my paper supplier