I agree with many people's responses, if you got a 5Dm3 then just use that, dont get a 7D nor a 70D.
Having used 7D for 4 years, and having just upgraded to 5Dm3 for a month, I really do feel 5Dm3 can do everything 7D does, even AF wise. AF on 5Dm3 is much more precise than 7D. And I rarely get all of the shots in focus with 7D when shooting at continuous high, so losing 2fps is not a big deal.
In terms of image quality, 5Dm3's so superior that I just really don't wanna get back to using 7D anymore. I had thought it could be my backup body before my 5D arrived but now I'm considering selling it. That extra reach with crop sensor doesn't justify me keeping it.