+1
...for reasons mentioned by others including simpler maintenance and the
ability to leverage useful postgresql-specific features. We're tasked
with making difficult decisions to be able to maintain our code,
including (IMHO) trimming fat like multiple database support.
Bharath and Awasum also brought up good points about existing
installations depending on other databases.
Users (e.g. banks / vendors / other paid support orgs) should chime
*here, now* with their real-world needs and data to help inform our
decision. Assuming we decide to proceed, users should also step up and
volunteer to write or sponsor mariadb/mysql to postgresql migration
guides, scripts, case studies, etc.