So I play a Mistweaver. I tested two different gemming strategies. Dueling the same person for each test.
Pure Int +160 in red sockets and belt buckle
Potent Vermilion Onyx +80 Int/+160 Critical Strike in yellow sockets
Purified Imperial Amethyst +80 Int/+160 Spirit in blue sockets
With this strategy, non-crit SM with 35.82% PvP Power from gear and no battle fatigue (45%) I was healing for 100k on average. Now with the 45% added battle fatigue my non-crit SM was healing for 54k on average.
Mysterious Imperial Amethyst +80 Int/+80 PvP Power in all red
Radiant Wild Jade +160 Critical Strike/+80 PvP Power in all yellow sockets
Stormy River's Heart +160 PvP Power in all blue sockets and belt buckle (and 1 yellow socket due to that bonus not being PvP Power)
With this strategy, non-crit SM was healing for 100k on average. With 38.82% PvP Power and 45% battle fatigue my non-crit SM was healing for 62k on average.
The difference in healing done is roughly +8k with gemming PvP Power.
So this is what I'm going to stick with. In 5.2 I sat at about 65% resilience and had great survivability so at this point there is no reason for me to gem for resilience.
Hope this helps.