I have two old Canon DSLR's a 50D and a 5D mkII, I'm thinking of trading them both in MPB have offered me £500 for both cameras. I want to put the money towards a newer model either a 5D mkIV or a 6D mkII. Looking at all the different specifications is making me cross-eyed. I like photographing wildlife, landscapes and generally walking/skiing/kayaking action type outdoor shots. Is there much real difference between the two? or would one be fantastically better than the other?