I didn't want to post this while the migration was happening, or even right after, because there was bound to be some proverbial stuff hitting the fan when the migration deadline finally hit.
BUT, with all of that insanity behind us, I do feel that it is high time to make a post thanking the Opalstack support team for getting us through the migration. The tools were great, and the support was fantastic.
I migrated a lot of sites, a lot of email addresses, and SSL too. I was braced for some form of IT chaos on my sites the day after the WF shutdown, and it just never came. Peace. Success.
Big shout out to Sean F, Peter D, and Klynton J. You guys are awesome!