Don't forget the overhead that comes with the ORM framework as well. I happen to be of the opinion that ORMs are good for prototyping and very small data model

Don't forget the overhead that comes with the ORM framework as well. I happen to be of the opinion that ORMs are good for prototyping and very small data models and one-off type projects but not for big leagues, production ready code. For that I would do as you describe and build my own data connector.