Holy architecture changes, Batman! 
I don’t think I’m still breaking anything here, but let me know if you think I am.
Update, 1555 CDT: My apologies to the handful of subscribers of my comment feeds, who’re now seeing the effects of me using the BirdFeeder Pepper for Mint and the BirdFeeder WP plugin.
How did the upgrade go?
It went pretty well. There are a lot of schema changes, so some plugins no longer work, but if you deactivate before you upgrade [which I knew to do but failed to do], you get benefit of a new activation system that checks plugins for failure before it activates them permanently. Took about ten minutes, most of which was getting up-to-date plugins.