I use SQLite with my flask app - it has 5/6 users connected at once max - and its excellent. I've run into issues with alembic when running migrations occasionally. I had intended to move to something "beefier" but I see no point, unless I have to really scale up.

Its straightforward, fast and easy for a casual DB programmer. Everything is wrapped in SQLAlchemy anyway, so all the complicated logic is in my Python code.

Which have been around ALTER_TABLE and CONSTRAINTS