"I have shot some footage straight off of the Canon C100 Mark II (mp4). I have also used the Atomos Ninja Blade with ProRes HQ (mov). Meaning, in my sequence for this film I have 2 different codecs."

With one of them being MP4, how? Premiere doesn't accept mp4 files on its timeline, you have to convert them to something different first. Or has this changed with the latest version of premiere?

Here's a related article that's worth reading. It'll give you a better understanding of using native iso's.
I tested it on the c100 mark ii and it stands true for that camera. I'd suggest testing it on yours too!

https://www.cinema5d.com/exposing-with-native-iso/

It's because you're shooting at iso320. You're losing latitude and information in your highlights. Shoot at the native iso850 and use the built in ND filters to get correct exposure. I shoot with a c100 mark ii and I never go below the native iso and I've never had any banding issues.

I don't understand the "broadcast specs" argument, because as I watch CNN, FOX, MSNBC, etc I see cell phone footage being played all the time. Those are huge broadcast networks and if they're able to play some quality looking footage from a cell phone that's way under "broadcast specs", I'm sure a 8 bit 4.2.0 dslr would suffice.

I was reading some feedback that Roger Deakins had given when asked about color grading and staying within the specs. He said he not having his footage graded based on specs, he's having it graded based on the emotion of the story and the vision that he have in his mind and he's not going to let "specs" determine the look of his film.

I don't understand the "broadcast specs" argument, because as I watch CNN, FOX, MSNBC, etc I see cell phone footage being played all the time. Those are huge broadcast networks and if they're able to play some quality looking footage from a cell phone that's way under "broadcast specs", I'm sure a 8 bit 4.2.0 dslr would suffice.

I've been a Canon c100 mark ii shooter, but now Sony may get a few of my dollars after all! Specs looks like it's a lot of bang for the buck.