After the recovery from a failed macOS 11 update, I finally got Monterey installed and all of my data transferred. If there was any fault involved it was on my part, not the installer and not Migration Assistant.

LESSONS LEARNED:
  1. Fallback Recovery System or not: the only way to revert to a previous version of MacOS requires a second Apple computer, a USB 4/Thunderbolt 4 cable connected to the proper Thunderbolt 4 port and Apple Configurator 2.
  2. Migration Assistant is noticeably improved and has more capabilities and options for a post-installation migration, but I still strongly recommend using it as a part of the installation/reinstallation process. It worked a lot better for me that way.
  3. I will still rely on Time Machine as my primary backup tool, but this experience has taught me the value of a daily CCC clone of the data volume. It reduced the restore time by roughly an order of magnitude. Admittedly much of that was because the Time Machine backup uses a USB 3.1 Gen 1 (nee. USB 3.0) connection and the CCC clone Thunderbolt 3, but there was a lot of untangling involved in extracting the roughly 1.25 million files transferred from Time Machine's snapshots that contributed significantly.


THE MOST NOTICEABLE FEATURES:
  1. A bunch of "this app is not compatible with this release of MacOS" messages as expected
  2. A Passwords preference pane
  3. Hide My Email

If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein