Upgrading gutsy to hardy with aptitude

[Cameron Hutchison]

I want to upgrade my gutsy installation to hardy with aptitude, since
aptitude keeps track of automatically installed packages.

However, the recommended method is to use update-manager since it may
perform some other actions to make the upgrade smooth. Is there anywhere
that these actions are listed? I would like to know what update-manager
will do that aptitude wont so that I can look out for the issues those
actions address.