Digital BW, The Print

>Is there any comparisons available that shows the longevity of 
>Ultrachrome inks vs. Carbon Inks such as f.ex. MIS Quadtones?

I don't know of any good, direct comparisons.  However, here is some
information that might help.  

My tests show that the black and light black inks of the UltraChrome inkset
and the MIS Ultra Tone inksets are virtually the same in terms of
light-fastness.  

The color pigments, however, are significantly less lightfast.  See the
Wilhelm 9600 tests (http://www.wilhelm-research.com/ at the "Epson 9600
(UltraChrome)" link on the left side of the page).  Compare the first set of
tests with the "B&W" tests.  For example, the first paper shown is Epson
Premium Glossy Photo Paper.  It rates 85 years under glass with the color
inkset.  On page 3, in the "Black and White prints mad with the full-color
Epson UltraChrome inkset" Premium Glossy rates 135 years under glass.  

The difference is the higher black/light black content of the "B&W" image.
Still, however, the "B&W" UltraChrome images made with the Epson driver (not
IP5) contain a lot of color inks.  So, the difference would be more if the
inkset used just carbon or the least amount of color needed to achieve the
desired B&W tone.

Note that not all quad inksets or MIS inksets are equal.  The Ultra Tone
inkset is the MIS state-of-the-art inkset.  It is based on their 7600
UltraChrome clone inkset.  The older inksets are not as lightfast.

Hope this helps.

Paul
www.PaulRoark.com