Update on my boot loop issue: Went to the genius today, and they were very kind (no scolding about installing the beta) and it took about ten minutes for them to install me back to 17. Since all my stuff was in iCloud and I didn’t want to have any chance of re-introducing problems, I went with a fresh install. If you have experience with a fresh install and you live in iCloud, it really only takes 10-15 minutes to get the settings setup as one might like, and I’ve found backups to sometimes take longer to restore, so I didn’t mind starting from semi-scratch.