Sorry, I've been dealing with real smartass posts on another forum. My apologies, really.
Again, sorry, I'll provide the information you ask:
For the overexposure, it was very interesting. I set both cameras to auto ISO, f/8, 1/30s, and the 5D3 read 10,000 for a +2EC whereas the 1DX read ISO 6400 for the +2EC. This is very, very fascinating to me. Do you know what it means? I'm not sure.
Why does ISO 6400 on the 1DX read +2EC but it takes ISO 10,000 on the 5D3 to read +2EC?