I've seen people with nearly 600, so this is good information... although in the wrong forum, since everyone knows that Rogues don't actually PvP.
What is _NOT_ known is if you continue to recieve the reduction to crit%, since it's far harder to test, but the crit damage reduction certainly stops at a tad under 500 and for good reason. You do not want casters getting crits that land for less than hits, and that's what you'd see at around 750 resilience on anyone who doesn't have a Ruin-style talent.