Ours is well beyond 8 years, and never gave it a second thought!

Oh, another question -- if you don't have a box spring, is it still comfortable with just a mattress, on a platform? (I'm wondering just how much a box spring provides in comfort level. We have a box spring set.) Lastly, as a tidbit I learned ages ago (not sure if it still applies), but (at least it used to be) that if you tried to shop around for the best set (hypothetical example only, let's say Serta, model 5 star), you could never find the 5 star model name in any other store. So you couldn't compare prices. Turns out that (years ago, anyway), the mattress companies had some sort of deal with the furniture stores that they'd make mattresses with different model names for each -- so a customer couldn't compare prices.)

Again, haven't looked for a new mattress in many years, so I don't know if that is still the case anymore -- hopefully not.