MySQL to Postgres

It looks like in 9.3 we are planning to announce that subgroups won't be available with MySQL (gitlab-com/www-gitlab-com!6079 (closed)). This will probably generate some questions from our PCF customers, who are all currently on MySQL.

I think the two main questions are:

1. What is the migration path for people on on MySQL using the tile? Will this have to wait until we add direct support within the tile for Postgres?
2. How much work is it to support Postgres?

To dig further into support, it seems like there are a few companies providing a tile but all are <9.6. One for example is Dingo Postgres, which seems to be a commercial release. Are these options even really suitable, compared to the officially supported MySQL tile by Pivotal?