Think there's plenty of missing tooling around postgres. But what are you lacking in backup with http://www.pgbackrest.org/ ? Or is it just that it's a separate package?
The point I was making is the lack of easy to use native features to perform typical administrative operations. When all is said and done, you may end up with a multitude of 3rd party tools to achieve feature parity with SQL Server , which is the particular comparison, and would be a limiting factor to implementing the platform in an enterprise that cannot withstand down time or tight RPO/RTO requirements.
In regards to SQL Server on Linux, I have just spun up (for testing) a three node AlwaysOn cluster with Pacemaker/Corosync, which is working quite well. Failover works as expected, however it is a tad slower than a Windows Failover Cluster. First impressions are very good and I would not hesitate to recommend the solution over a PostgreSQL or MySQL implementation. It is far less complicated and provides excellent HA and recoverability options.
In regards to SQL Server on Linux, I have just spun up (for testing) a three node AlwaysOn cluster with Pacemaker/Corosync, which is working quite well. Failover works as expected, however it is a tad slower than a Windows Failover Cluster. First impressions are very good and I would not hesitate to recommend the solution over a PostgreSQL or MySQL implementation. It is far less complicated and provides excellent HA and recoverability options.