A little while back, my guild was wasting time around a raid (can't remember if it was just before, or just after a raid) and a few of us were meandering around the Dal Sewers.
While I will run the occasional BG (Wintergrasp in particular) I VERY rarely duel. However, a guild mage, and a guild warrior (among others) were bashing each others' heads in
I swapped over to my PvP gear, and went at it with the Fury Warrior. I won by about >< that much. (he was in PvE gear, so he hit like a truck, but had no resilience) and then went up against the mage.
He was dead after not THAT long of a fight, and I was still well over half health.
I swapped gear, and let my cooldowns cool off, and the mage & I went back at it. He pretty much 3-shot me.
Granted, I did NOT use my stuns as well as I could have, but I hardly had a chance to get near him to even use them. In the first fight, I could be a bit sloppy, and survive long enough to get close to him. The second time around, not so much. Ouch. I was dead and he still had 90% health (or there abouts)
And by the way, Seal of Justice is pretty dang useful, especially against a caster. It gives me 3 extra stuns (though they are short and kind of random) which helps interrupt AND gets me 2-3 extra attacks.
But yeah, the mage & I were both shocked at how much of a difference my gear sets made. (and it was a big difference)
I also think that he wasn't "ready" for a Ret during the first fight, so I had an easier fight the first time. I was able to get in close, break LoS by running through him, etc. Whereas the second fight, he maintained a good distance and wasn't even really even threatened. Gear was one part, but he also fought better the second time.
As it stands, I have ~850 resilience in my set: LINK