Well, I trust Gigabyte, I've had my card almost 3 year and it's ok.
But really,whether to buy a factory pre-OC'd card that comes with warranty is up to the original poster, and what he feels like doing. Some people would recommend some things, some people would say otherwise but it's up to the original poster what he thinks, after all, newegg does have customer reviews to back up how a card that you can buy there really performs.
Anyway, let's not keep on arguing whether OC is good or not. Sure, there's problems if something isn't done right but that's not the goal of this topic to begin with.