Here is a write up on the EOS 1Ds MK III:
http://www.todayonline.com/articles/230365.asp"Surprisingly, the camera's high ISO performance is not on par with that of its predecessors. Don't get me wrong; the noise performance is still good. But at ISO 1600 and above, noise grain is harsher when compared with my company-issued EOS 1D MKII."