I'd look into Postgres more first. They have some features that give you some of the convenience of a document DB. I'm not an expert but from what I've heard st

I'd look into Postgres more first. They have some features that give you some of the convenience of a document DB. I'm not an expert but from what I've heard stuff like JSON/XML tables and customized column types that can store things like arrays and other structured data instead of just scalar data. It sounds pretty powerful and I've been told it is rock solid. That being said, don't buy into the anti-mongo hype so easily either. It's been overstated and for a large portion of the middle-ground on scalability and performance mongo is great.