How long do you intend a print to last? We have a paper print taken of my great grandfather and his family in 1889. I doubt that they intended us to be viewing it in 2004, but maybe they did. Anyway, it appears to have not faded, and has not stained or silvered out. It was stored in a box of papers for most of those years, hardly what you'd call "archival".

So I use fibre for any prints that I'm pleased to give or display. Even prints that are produced for a short term purpose, such as displaying actors in a theatre foyer, can end up valuable souvenirs. Since most people's colour prints will be crap in a couple of decades, I'm doing my bit for posterity, as far as I know.