It's a big topic. I'll give you my take and others will probably chip in too.
Firstly, dye prints straight out of the machine will fade more quickly than pigment. Just how they compare "as-is" isn't clear to me, but pigment is much more long lived.
Pigment has bronzing and gloss differential problems on glossy papers, dye prints have an even gloss and no bronzing.
Most art prints using pigment are therefore done on mat papers.
There are some good products designed to coat dye prints which give them a longer life.
Generally, it might be said that pigment print heads don't have the same life expectancy as dye ones.
It's a huge topic with many threads for you to look at. I suppose the most asked questions among dye print people is, "How long, hung indoors and coated with professional spray products, are my prints going to last. The "going-to-last" bit is also debatable.
MHMG at
http://www.aardenburg-imaging.com/ has the best data available on the topic.
Finally, because the T 120 uses pigment black, it is fast and reliable and cost effective for plans and drawings in, say, architecture offices.