That’s not a recommendation that you do so, mind you. It’s just the story of a few minutes in a day of my life.
The resulting install generated a warning in the mail logs of “do not list domain [hostname] in BOTH mydestination and virtual_alias_domains,” which was easily corrected.
The contents of /etc/webmin/postfix/version also had to be manually edited, and Webmin restarted, to make Webmin / Virtualmin aware of the change. Ilia says that will be automatic in an upcoming Webmin update.
I have had no problems since the Postfix upgrade, which was a few days ago, including using SNI with no hiccups.