I agree that Gray hits harder. But Edgar's faster. And he floats like a butterfly. And he hurt Veach standing so we know he at least has the potential to do so.
I think on the feet he'll frustrate Gray, just like he did to Sherk and just like he did to BJ.
As for the wrestling, I would probably still have to give the edge there to Gray, but at the same time I wouldn't be surprised to see Edgar turn the tables on him. It all depends on how much both guys have improved in that regard since their first meeting.
At the current odds, I'm willing to bet that Edgar can win this. If the odds were reversed, I'd probably be on Gray.