I have a 7d, a 5d3, a 1d4 and now a 1dx. The 1dx does everything those other three do plus more. I am not a pro, but I don't miss the other bodies for 1 second. If you aren't doing a lot of high speed action shots, I would urge you to get a 6d though. I love bif photography which is why I upgraded. I also shoot mostly low light situations. 5d3 is nice, but not fast enough at only 6fps. I might keep the 7d for birds in the wild, with my 600 f4 version 1, but I doubt it. 1d4 is great, but not as user friendly.