Yeah, I would still consider the 1D3 the backup. For what I shoot, the 5D is just so handy. I love the true focal lengths of the lenses on the full frame, the shallow DoF, etc.
Each body has its pros and cons, so I can't really say that I prefer one over the other. If someone hires me to shoot their kids' hockey game, I will go with the 1D3. If someone wants some nice portraits in the park, the 5D. These two bodies really do complement each other very very nicely.
I am totally agree with TaDa, and I am doing the same thing ! 






