The Endpoint client install simply installs Sophos AutoUpdate and then the Communications piece - AutoUpdate then streams down the remaining content for an installation to take place.
I'd prefer if the Endpoint 'seed' client, once it gets to the stage of downloading content that the installation could be 'completed' and instead continue on in the background.
The user wouldn't notice the AutoUpdate lient downloading content, and if the system was turned off or shutdown, the AutoUpdate client will gracefully resume.