I can attest that pgbarman works great. cough I accidentally nuked a production server once. However thanks to barman the downtime was only tens of minutes.
It works by making a full backup at fixed intervals (say weekly) and then "pretending" to be a replica which makes it receive all the changelogs in realtime. (Basically it receives and archives WAL's). This makes point in time recovery possible.
I've used Barman for physical backups (I used the streaming backup option). Works well, though it's a bit of a slog to get set up the first time (the docs can be confusing in some areas) but once it's up it's great.
Does anyone else have experience between the two options?