Jason Wigginswrote a review of KMC X9SL Chain - 9-Speed on March 15, 2015
Familiarity: I've put it through the wringer
I cannot break this chain! I bought my first X9SL after destroying 2 shimano chains in the same month. This chain lasted 4 years through very aggressive trail riding. The reason I retired it is that the nitride coating was wearing off. No stretch!
I love the gold coating as well. This is one of those cases were bling and performance are wrapped up in one package.
Assembling bike after winter tear down and tune with a shiny new X9SL