You're not the first to try this. Sapphire (the framework powering the SilverStripe CMS) implements this technique and has all of it's DataObject select calls r

You're not the first to try this. Sapphire (the framework powering the SilverStripe CMS) implements this technique and has all of it's DataObject select calls return a 'DataObjectSet' which is basically the equivalent of your DB_Iterator.