The more I read, the more indecisive I become!

This is a little bit about the new Epson UltraChrome K3 inks which are used in the R2400 but not in the R1800...

Epson UltraChrome K3 ink technology represents a turning point in the history of inkjet printing. Inspired by our past generations of pigmented ink technology, Epson's all new 8-color ink set incorporates three unique levels of black, which along with new color pigment technology, dramatically improves both color and black and white prints. Imagine producing archival prints with amazing color fidelity, gloss level, and scratch resistance, while providing stable colors from the moment prints exit the printer.
Read the whole article at Inkjet Art