The 4900 is a pretty slick little machine, and represents the consolidation of the new line. With the X900 representing the high end and the x890 representing the lower end line. I was a little surprised to see the X890 announced, but really I think Epson has to respond to the slew of technical printers offered by HP and Canon, and for the proofing, architectural markets, and certainly a number of photographers this will be a pretty compelling printer, and expect these to cannibalize a piece of the x900 market.
While I don't see the 4900 having any published features that would put it in a league above the 79/9900 it does represent a big leap forward. They showed this off at a dealer meeting in spring, and I think they really went back to the drawing board with this one, and while it shares the ink and heads with it's bigger brothers it's really a new machine. It uses new ink carts, and the size has changed to 200ml, and the carts are all now completely internal. Also I expect that the false positive nozzle cleaning should be improved with this model. Also the fact they are offering a spectro with this is a really cool feature.