Update: I ran a test update on a copy of my forum and it went through with no problem. I had disabled all plugins except for the 2.0.x patches (15, 14, 13, 12). The best part is that it fixed a problem I've been having with
bad links for attachments (images, .docx) added prior to 07/16/18. The personal avatars were not fixed, but they're not as big of a deal.
At the moment everything looks great, but if I encounter any problems, I'll put them up here. I realize I shouldn't us RC2 on a production site, but it sure is tempting.