This may be a stupid question, and I’m asking in this thread instead of the empire thread because I didn’t want to rain on its (well deserved) parade. I don’t know much about vfx work, but I’ve always wondered if you kept the project files and separate layers unrendered for a project, if, say, a few years down the line they finally release a better transfer of the films if you could just replace the base file in your editor and have the changes applied to the new transfer without having to do much besides tweak if there’s cropping differences? Sorry if it’s a dumb question but I’ve always wondered that.
If your work was at the appropriate resolution of the new material, it would certainly be usable. But it would not be as simple as updating the source of the main film in your project. As you say, there are cropping differences. So anything that’s overlain will need to be scrutinized closely and adjusted. But you would also need to adjust the color timing, contrast, and potentially grain of all the elements so that they match. That’s still all a lot better than starting from scratch, but you need the right elements to begin with.