Originally Posted by dsbrantjr

All links wear out eventually; power links last well but are not immune to wear. If you have worn out the chain with the power links installed, you might consider that the power links are as worn as the chain and should be replaced soon. Having said that, they are probably a better bet not to fail suddenly than the reused Shimano pin, at least for the short term. I'd suggest using them on the new chain until you can get new ones.