You are right. Though the updates can be found here......http://autoinstall.plesk.com/PSA_9.5.2/microupdates/http://autoinstall.plesk.com/PSA_9.5.3/microupdates/
...those are only files that need to be handled in some manner.
So the only way is runnning the autoinstaller or Plesk GUI?
That sucks since it's security related.
Only if you check manually with the autoinstaller or the Plesk Gui you will notice.
How stupid is that?
EDIT: Found an Parallels KB article that confirms this procedure:http://kb.parallels.com/en/9294
And they even use this way in Plesk 10. How insane!
I would like to express my compassion for all admins that have to supervise many servers.