CatBus said:

Found it:

The difference in detail is barely perceptible (aside from the color shift from the imperfect attempt to match color grading). But yes, encoding at 1080p would allow those barely-perceptible differences to be included.

I do actually see a very noticable difference in image quality and detail between that 1080p and 720p shot CatBus, perhaps its my large monitor that makes the difference easier to see.

Thanks for that explanation Harmy, I can see why you wouldn't want to redo everything from scratch in 1080p. I wouldn't be in a rush to redo my Semi-Specialised Editions either if I lost all my project files and sources.