I've changed all blue / yellow to pvp power / resil gem, with red slots still main stat. Since the socket bonus is usually resil, I'd be loathe to gem to pvp power in a red socket. How's that working out for me? I dunno, I was globalled before and I'm globalled now.
I'm rocking 30% PvP power on my ret, loving it. I've gemmed pretty much all PvP power, with the exception of 3 pure strength gems to keep my meta gem working. Is it better than normal gemming? It's hard to say, however my enemies usually get shit on by me in 1v1s. Ret is a rather strong class for 1v1 either way though, so hard to tell.
Edit: In random bgs I pretty much always top the damage, depending a lil bit on how much I decide to play support with offheals and such.
Resilience RATING's effectiveness decreases the more you have. The actual reduction that you gain from resi actually gets better each aditional % reduction you have.
And PvP power is exactly linear.
In general, it will be better to use full red gems and use pvp power hybrid gems. This is because the extra agility or w/e from the red gems will benefit from the pvp power. Think of it like this- if you had 0 intellect and 100% pvp power, how much damage would you do? For mages the scaling is basically 1 point of intellect per 3 points of pvp power for max damage. IDK bout the other classes.