We tried to use the database diff recently to compare our development database with our production database but could not succeed. What we actually wanted to do was compare schemas. Our connection to the dev db uses the main schema but in production we only have access to the main schema via personal read-only accounts. Therefore what the Database Diff allowed us to do was compare our personal production schema with the main schema in dev. It would be more useful to us if there was a way to choose a connection and then a schema to compare under that connection hence allowing us to compare schemas.
Thanks for listening!
You can do this today David.
I explain how here, but basically if you set the option to 'Mainain' it will use the object owner in the source connection to determine object ownership in the destination connection.
We're looking at improving this, along the lines of your suggestions, in a future release.