Based on my experience so far, I would wait.

yes we do it at BH Media for two of our sites.  we run subscription as plus so every section has google surveys but the plus sections are hard walled.  non subscribers get ads but subscribers either get no ads or ad lite which is only specific ad sizes like leaderboard and Right which is 300x250 or 300x600 top of right rail.  you can either do this with custom code or if you ads are townnews blocks then you can add an audience of subscriber this also requires that you have TownNews IQ for the audiences.  you can see this on Omaha.com and Richmond.com.