I had a 1d3...and I so wanted it work- because in so many ways its the perfect camera imo, but I couldn't get it to focus properly...in spite of sending it in to Canon- nada!
If you want to go 1d body, seriously consider waiting for the 1d4 or get the 1d2n....I choose the Nikon route, but thats just me. If the 1d3 had focused I would have never left and been a very happy camper.