The 1D can AF so sharp and it's method of processing is elevated significantly out of the camera, you can 2X double images without much enough loss of IQ on a 1DMKII and the 5D is slightly larger image since the sensor isn't cropped, but the AF and camera reaction time is so slow that moving targets almost never come out clean or in focus; so it's a waste of effort. For stills the 5D would still be below the 1DMKII to me, it's larger sensor still don’t make up for all the awesome in camera processing the 1D MKII does, I rarely have to PP my photos since leaving the 5D. The iso on the 1D MKII is noisier, but not up to iso 800, and 800-1600 compared to the 5D are less good; the 5D has slight advantage at iso 1600 but not enough to offset anything else it does slow/wrong.
Photos were simply impossible for me to take with the 5D and the 1DMKII does it effortlessly.
I don’t rattle the shutter off, I just take the 2 or 3 I want; click click click and they all rock. I take 3fps hold down trigger with the 5D and all would be out of focus. lol.