A few days ago [Stuart Langridge](https://www.kryogenix.org) and I upgraded a machine from 8.04 LTS to 10.04 LTS and then from 10.04 LTS to 12.04 LTS, all over SSH. Both upgrades ran without a hitch. We simply ran `do-release-upgrade` and everything worked great.
Upgrading from a four-year old installation to a current installation with no problem was impressive. For everyone who contributed to making the magic happen, thank-you!