I'd just like to add that having all the users in one database has
another minor disadvantage:
If you want to make use of PITR for your clients, and client A shares a
postgres instance with client B, and client A asks to be time warped,
then you have to time warp both, since both are in the same db instance.
Granted, that's sort of a minor issue, but something to consider.
It could become an issue if you have many clients sharing that database
and it would cause downtime for all those other clients while you're
warping back to get someone's lost data.
However, you don't lose all of the benefits of PITR. You still have the
capability to do incremental backups.
Regards,
Jeff Davis