Depends. I was approach as well by TGN representative. But I was able to negotiate deal a bit better than freedom. So in that case, why shouldnt I give them chance?
Again, depends on who contacted you. Had some false claims on music (properly licensed) and I just asked for help a guy who recruited me (and gave me his contact for these cases) and got helped pretty quickly
One troll or overzealous fan and unless you REALLY know to defend against it you might get banned from adsense forever. Also dont forget Google pays after $100 while network can pay as little as 1 cent (after its 40% or less cut).