Yeah, I am extremely skeptical of these 'accelerated' tests done on inkjet inks. It's a big marketing ploy if you ask me, and it's obvious people are totally buying into it.
They do a good job of testing what they test for, but there are many, many unimagined things that can go wrong for a print. Epson's already had a fiasco where an inkset that was tested for 100-year archival stabilty turned out to have an unanticipated chemical reaction with many (but not all) papers that left them lucky to make it to 18 months.
There are far too many good ways to make a print--even for those of us who've embraced the digital anti-christ in whole or in part--to waste time on inkjets.
I can imagine a day when digital cameras are good enough to make me abandon my 2 1/4 and 4x5 film cameras--although I think it's 20-30 years out--but I just can't make myself imagine inkjets ever being a good replacement for photochemical prints.
Remember the Epson Inks that were rated for 200 years? In actual use, under certain common conditions the light cyan dye would start to fade noticibly within HOURS! I think that they blamed it on the paper but I never followed the problem to it's resolution. It's not hard to be cynical about accelerated tests and wild claims made by marketing people.
That is called grain. It is supposed to be there.