New or "new" fork tradeoffs
I'm casually looking at forks to upgrade my xc bike. After looking at ebay and online retailers, I have a question. Would it be better to get something like a used SID, something like a newer used Reba or something like a new Tora?
I ask this because obviously the SID (or Vanilla, etc) is a much better fork, but when do the technological advances made in the last few years outweigh (older) high quality?
I guess I'm asking how old is too old for a used fork, and what I should look for.