Might I ask a question which might seem quite uninformed?
My own camera is a 5D II with grip, and I am also now borrowing the 1Ds III. I have previously borrowed the 85 F1.2L, but then shot it with my 5D II. I had to throw away most of the pictures I shot with that combo (ca. 80%), and that is the reason I went with the 85 F1.4 Sigma instead (that and price of course:). I have now also borrowed the 85L, and I am using it on the 1Ds III, and I have an exponential growth in keepers.. This might be because I am getting better at taking shots, but I cannot shake the thought that the combo of the AF on the 1Ds III and the 85L works better than the 5D II and the same lens?
the 1D bodies deliver higher voltage to AF on lenses giving them a bit more speed I think the 85L performs better on a 1D body than 5D for this reason