There's two schools of thought, I went through nearly the same thing with my old 1D2.
Got the 5D3, can't imagine I will ever pick up the 1D2 again.
That said, I paid $4,500.00 for that 1D2 way back when,. and now to sell it for just $350.00-400.00 or so? It's here as back up, and could be a great gift for someone looking for a real workhorse.
So I kept it.. so far anyway.
If you don;t have any other option for a back up.. I'd hold onto the 40D for a while anyway. It sucks when you have no camera.