At the suggestion of several of you, I ran a few moonlit clips through a de-noiser (Neat Video). I'd consider these a moderately aggressive denoise pass...I've left a little noise and then sharpened it slightly.
Consider. Me. Floored. The ISO 20k clip in the middle is a little smeary...but honestly. I think it's impressive what the C300 maintains in terms of Detail and DR at 10-20k iso. Download the original file to bypass Vimeo's own denoising.