[mgrassotti]

I do it all the time in early stages of app development, moving between SQLite/MySQL/Postgres.

Once you get into production it's a different story. A good ORM makes it easy to swap to a different DB without need for code changes. What it does not help with is the much bigger problem of how to migrate the data, indicies, backups, replication, etc. that you'd have in place for a production database.