I could be wrong but from what I see/read, this ORM beast looks like many horse-driven carriages are trying to push a train forward from behind = oxymoron.
Why such a claim?
The the relational database world, an ERD is a MUST, such an ERD is better designed and developed by a database professional who truly has solid skills in relational database theory and RDBMS(s) AND understands the given business, thus, the database he/she designs and develop will work well and reflect the needs of the business. DDL (Data Definition Language) function should be limited to such database professionals only, not web application developers in general.
If ORM tries to mess with ER, the integrity of the database could possibly be in danger. If I’m the DBA I would be mad as hell.
Having said that, ORM may be considered for DML (Data Manipulation Language) for insert, update, delete and select, that is data read and write.
This is just a quick observation, so, in no way of thorough thinking…