I've noticed this too. I did av from 71-80 and singed with ilvl 213 pvp gear which was way better than anything in naxx 10 and heroics, so even for pve I use pvp gear. The survivavility of pvp gear in raids is nice, aoe dmg boss fights are cake, as I approach tank like hp.

I've found that spec makes more of a difference than gear, so I just bought dual specs on all my shaman and will be pvp ele and pve ele. Mostly the same gear, swap out trinkets, and a couple items with hit, and bam I'm a viable raider