I've had the 1DMkIIN and the 1DsMkII. Both are superb bodies. As you know the N is a 1.3 crop, but great for sport. When I shot surfing with it I would often get a burst of 18 shots, great for capturing that special moment. The 1DsMkII was not as quick on the burst but still very good. For me, the 7D cannot compare to either of these superb pro bodies. And they have the bonus of being far more robust and waterproofed.