Power conditioner -- when to replace?


I just bought a Furman power conditioner for my bedroom system to manage all my cords.  While investigating power conditioners, I came up on a couple of sites that suggested that they lose their effectiveness after as little as two years.  I have a beefy PowerVar 12 Power Conditioner that I have had in my main system  for maybe 10 years and I got to thinking that it might be at the end of its life.  

I welcome any thoughts on this longevity issue.  Thanks. 
whitestix
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Thanks for all the input, it is very helpful.  To Elizabeth's last point, the usefulness of a "power conditione" includes both functions, typically.   Frankly, it the surge protection is kaput after a period of time, then one is left with only power conditioner and no protection for their gear in the event of a voltage surge.  I think both functions are equally important.  

Question:  is there a way to discover if the surge protection is still effective in a unit? 
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