okay here's what ham does over apt / fapman: It does the reboot properly after the upgrade It locks the device into flight mode while updating It turns off most system processes and the desktop to avoid conflicts when deploying the update . . . It simply does a System upgrade in a safe way, whilst apt and fapman run it in a way which is suited for application upgrades but not exactly for system upgrades which possibly flash camera firmware or do similar risky tasks.