Buying used: how old is too old?


All,

Considering buying some used speakers from a well established company, e.g., Wilson, Focal, B&W, etc.

Aside from obvious technology updates, do speakers have a shelf life? If so is this measured in overall life, or number of hours played?

I’ve read some reviews that some speakers can really improve with age, no doubt longevity is going to be influenced by speaker drivers. Perhaps paper breaks down before other materials—I don’t know.

Old flagships can be bought for a fraction of their original cost and less than new mid-level speakers. No break in needed! But maybe they would be broken down?

I’m sure there have been numerous threads on this topic, but I didn’t find much in my search and am also interested in any recent experience on the topic.

Would be really interested to hear thoughts, opinions, and experience with this.

Thanks!
w123ale
All I know is this: I bought a pair of Klipsch Cornwalls from the early 80's a couple years ago, and they sound magical; it was the best $800 I ever spent.
My Seas Thors sound EXACTLY as they did when I bought them back in 2004.
Richard Gray advised me on upgrading the Millennium tweeters , which i did, and was a big mistake, = out $700,
Richard tested the old ones on his ohm tester and found a tiny miniscule fraction of a ohm off,,so I bought a new pair, Out $700 as they sounded exactly like the old ones. I since dumped the Millennium tweets at 1/2 price and will never ever go back to dome tweeters, I use a FR/PS for mids Far superior to all dome tweets. Like the one you have in your speakers.
So old vs new, = same speaker. 
A guy just bought a pair of Infinity Delta Gamma's for 150 bucks, he's posted on audiokarma. How's that for a deal!
My oldest loudspeakers are from the 1920s I have drivers that are about 90 years old that are still working well. But that being said avoid modern loudspeakers over 15 years old unless they are horn-based designs. Standard dynamics used ferrofluids in VC capacitors that drift after 15 years and rubber or foam surrounds that rot. The oil in ferrofluids dries up leaving Metalic particles in VC. Sure this can be repaired but unless you want to do so consider newer loudspeakers or those made before 1970. 
Three years ago i bought a pair of 17 years old dynaudio contours 3.3 for 1200 euro. They sound much but much better as the new dynaudio contour 60 i also own. The 14 years old genelecs i have sound better as the new dynaudio contour 60. Wait wait wait!!! The almost 40 years old bose 505 worth 300 euro sound way more natural and fun and big as the new dynaudio Contour 60. It’s not my personal opinion. And you save health by getting speakers which are already burned in!!! For my dynaudios Contour 60 it was 500 hours which can take one year in normal disappointing listening sessions. Good luck!