PVP Power should still scale better than your main stat. PVP Power should only be gemmed if your playstyle/comp is extremely defensive to where you don't really need to gem resilience. Typically, you should gem resilience.
As a Ret, you *need* to gem Resi. It's not an option. PVP power only adds to half of our class (damage component) and doesn't affect our offheals and stuff. At most, if you're covered by good heals you can afford 160/160 Power/Resi Gems.
I suspect for many other hybrids e.g. Ele Shaman this is also true.