The upgrade went flawlessly I'm happy to say.
Live major version upgrades are one of the features that keep me using Debian. That machine's down time during the whole process was < 15 seconds. Literally the time it took me to reboot.
I performed a major version upgrade to my wife's Mac. It was unusable for > 3 hours
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko