Hmm.
PvP power affects whole World PvP so if you add your PvP power which is around 50% to your heal you should heal for that amount.
Enter a PvE instance you will see a drastic change in your healing, which means PvP power benefit is lost and no other stats will change.
I have tested this yesterday on my restoration druid, using regrowth.
Stats: http://image.prntscr.com/image/b5368661cbd548ca9b1f586706da8584.png
In the World PvP my 551 Rdruid was healing 247 approx regrowth, on the other hand, other druid healed for approx 183-187.
Which means, even tho the PvE druid has increased stats in PvP world it doesn't matter.
Eventho tooltip on PvE druid was higher than that on PvP one, PvE one healed less.
When we entered Siege of Ogrimmar, 551 druid was healing 120k per regrowth, 562 healed 150, which means PvP Power benefit was lost.