FF 7D2 = 5D3 (ish)
I shoot the two side by side and find them virtually interchangeable from a control and performance stand point.
Needless to say when shooting both side by side, I have the longer lenses on the 7D2, and the wides on the 5D3.
Before the 7D2 was out, I would use just the 5D3, or pair with a 1D when shooting long lenses.
If I shoot one camera, it is again one of this pair, and decide which depending on lenses and lighting.
ie: The 7D2 is a great and affordable camera, If you lust after it's features but want FF then go for the 5D3.