The best strategy for PvP right now seems to be... play PvE and level up your heroes as quickly as possible. At least from my perspective (including my defense), PvP seems pretty quiet right now. Wonder how Playdom thinks things are going? (I mean what they really think, not just what they would say in a Facebook announcement or whatever.)
It does seem that there is a pretty good amount of rage surrounding PvP right now from a brief survey of comments on the Fb page.
If enough of their metrics tank, I bet we will see more changes soon.