To keep a poster from deteriorating, I think linen is fantastic.
To put linen on a poster that is rolled and basically doesn't need it seems frivolous and a waste of money, but different strokes for different folks.
To dismiss linen with a clean sweep of "LINEN SUCKS" seems a bit silly.
Indeed.
Ultimately, it is what an individual collector wants to do (referring to the backing of newer, folded posters), in trying to diminish or erase fold creases or lines. I am of the thought, too, that less is more. If a brittle, fragile poster can be saved thru conservative backing, then I am all for that. The alternative is ending up with a pile of dried, flaked paper, in many cases. That being said, (IMHO), i think that (even older) posters that are overpainted or made to look new is doing a disservice to that poster, when much of the art is buried beneath a thin layer of paint, in order to make it sparkle and shine.
Many want or desire this look, we all know that. Personally, the few posters I have had backed were left as is, with only the most minor of cross fold separation touch ups on one french panel, from the 1920s. I like to see the "life" a poster has lived, so small border nicks, chips etc don't really bother me. Same goes for an older poster whose 60-70 year old border may have tanned with age. I would prefer to leave it, rather than having it be given an airbrushed "face lift."
Jeff