The disadvantage of the xml process is, that it has to be maintained manually by us.
The xml process has the advantage, that one can control what updates are really being presented to the unsuspecting enduser. Sometime, a simple apt-get upgrade or apt-get dist-upgrade can be recipe for desaster (dist-upgrade more so than a regular upgrade).
I am in favor to keep the xml process, and let people, who use the commandline anyhow, use the apt-get procedure.