There's never really been a question that I'd want to revise the older material. Even if only because I've done 99% of the world-building after the first one. Going back and layering in hints of the larger world and history (and "correcting" things I've changed) is essential.

My only real question is whether I want to try to engage an actual content editor to work with me, or simply a text editor. A lot may depend on whether I can identify someone I felt I could trust for the former.