Back in the old days, way before 9.0 was introduced, people had to use Slony to replicate data. The core problem with solutions such as Slony is that there is a need for a changelog trigger, which actually writes data twice. Trigger-based solutions are hard to administer, are not able to handle DDLs, and are in general a bit tricky to operate.

BDR has been invented to put an end to trigger-based solutions and turn PostgreSQL into a more robust, more scalable, and easier way to administer solutions. Trigger-based replication is really a thing of the past, and should not be seen in a modern infrastructure anymore. You can safely bet on BDR—it is a long-term, safe solution.