I have had the 1D III for over a month, but hardly used it much. In my initial use of the camera I didn't find its image quality much better than the 5D, and there were some focusing issues, even with One-Shot AF. I have spent the last two days reading Rob Galbraith's write up on the 1D III's focusing issues, and trying different settings. I took the camera out this evening and tried it out and noticed great improvements, at least on my 85mm f1.2L. Focusing was quite consistently accurate, even at f1.2, using AI-SERVO, as well as One-Shot.
With the 50mm f1.2L, I found that it needed focus adjustment of about -5. Shot around the house on f1.2 and I am happy to say focus was very accurate. This is very encouraging.
My next test would be the action tracking with various lenses. I will start with the 70-200mm f2.8L IS this weekend, and see how it goes.
Megan -- Canon 1D Mark III with EF 85mm f1.2L II @ f1.6, ISO 1600. Larger Picture.