The portion after the do-release-upgrade will take quite some time as it will dl anywhere from 500MB to 1G, and then as it upgrades lmce components from 1004 to 1204, database updates can take a considerable time. By contrast the do-release-upgrade portion dls approx 880MB on my systems. So total upgrade is > 1.6GB of dled .debs. Keep this in mind.
Otherwise, I have had success with the script. Please keep in mind that upgrading to 1204 is not an option for a production system, there is a lot
that does not function properly.
If you do attempt this, please file tickets about anything you discover is not working, check to make sure no one else has reported it first. http://svn.linuxmce.org
Thanks for all everything polly! I'm hoping we can have a clear upgrade path for people from 1004 to 1204 once things are more stable.