One important benefit of using an ORM is not being locked in with a particular DB server tech. Good luck migrating large app not using ORM, from, say, MySQL to Postgres if, for example, Postgres replication is something you are all of sudden interested in.
Has anyone ever actually migrated a database on a non trivial application? I want to go from MySQl to Postgres, but I am not sure if its worth the risk / effort. We got told about the standard nature of SQL in University, and how you could swap engines 'easily'. Then we started using them in real life and the reality of that situation hit.
