Thanks again!
Looks like we are ready to upgrade production Zimbra+Samba to 5.0.2. The upgrade of the test server went well after several re-runs from scratch due to certificate and samba-related issues.
One final (honestly

check. Is there a suggested procedure of upgrading samba stuff?
Should we undeploy Admin zimlets on 4.5.5 first and remove posix/samba classes BEFORE the upgrade or upgrade first and then replace them on 5.0.2? Does it matter at all?
Could it be more prudent for a crucial corporate installation to wait till 5.0.3 and then upgrade?