Best Database

We have been using SDP for years and have our DB on a MS SQL 2008 server. It's time to decommission that SQL Server so I have to migrate all the DB's to a new server. For SDP I have the options of SQL 2012, SQL 2016 or take a totally different approach and use PostgreSQL on the SDP server itself. I like the idea of keeping the DB local to reduce network traffic and making things easier with VM Snapshots not having to worry about keeping the SDP server and DB in sync.

I am of course concerned about performance. Our current DB file is about 6 GB in size. Has anyone done any performance testing with SDP on a remote (10GB LAN) MS SQL vs a local PostgreSQL DB?