Upgrade might not be the right word. Currently doing sports with a 5D4 and a 7D2. I am finding I like the 5D4 for quality but it lacks in the FPS. I am looking at 1Dx but not sure if that is going to a good enough upgrade/compliment to my 7D2. I would use the 7D2 and whichever other body I got. Will I be missing a bunch if I dont save up for the 1DxII and get a 1dX?