I have both... and the 1DmkIIn that I currently use was purchased primarily for sports. It makes my 70-200mm a little longer so I'm enjoying that aspect of it. I don't need the wide angle when shooting sports and action, so I don't miss the extra space in my FOV with it. For landscapes (which I don't do much of) I would certainly use my 5D. For portraits... I 'd use either... but more likely the 5D for the extra sense of depth. I say there is no reason for it to be FF like so many are complaining about. The 1DsmkIV is not far off and it will be FF, and the 5DmkII is already on the market and that is FF as well. Why does the sports/PJ body have to be as well? Just because the Nikon is? If there is something to complain about with the current Canon lineup is that the AF system on the 5DmkII wasn't revamped to be at LEAST what the 7D is using... though I would prefer the system used by the 1 series on it.