Well I have a pair of 1D3s and a 7D (plus a lot more, lot more). The 7D is a perfect mate to the 1D3, totally in a different league than any of Canon's 1.6 crops. Occasionally I am firing the 7D and have to think twice to make sure I am not shooting with a 1D3. I would think that anyone who had a 7D and a 1D4 would be a very happy person with capabilities to do just about anything.