Wilhelm-Research has published their study as to the print permanence of the new UltraChrome K3 inks. They used a pro printer, but the R2400 uses the same inks, so this should apply.

Some incredible print longevity numbers when using certain papers, especially with "three ink" black & white printing!!

http://www.wilhelm-research.com/epson/9800.html

150, 200 and 300 years.

Some of the prints are more archival than any other type of prints made with current processes.