My upgrade took quite awhile. Give it 30 minutes and reboot.
Upgrade (Xfce) via the terminal was flawless. The only "scary" thing was a mismatch at the beginning of the process, which I chose to "ignore mismatch and proceed anyway," figuring it would be resolved by the upgrade.
Thanks to @ericbsd and the team for all the very tedious work it must have been to produce this upgrade!
I'm curious about one thing: I had uninstalled some apps before and replaced them (Brave over Firefox, Evolution over Thunderbird, for example), yet they appeared to have been reinstalled during this upgrade. But they don't appear in the applications menu, so I guess they weren't. Perhaps they were just being added to the available stuff in Software Station?
Again, many thanks for a flawless upgrade and a nimble, blazing fast OS!