For my ‘Yub Nub’ version of my ROTJ project, there are two entire scenes sourced from 4K83. I found that gradually fading in some film grain and/or gradually fading it out afterward to be useful. They’re just too different. However, if I were ducking between sources very often I imagine a layer of new grain over all UHD footage would be necessary.
Well done. I will disengage self-destruct initiative.