The entity config query is in and the aggregation query system is ready, and it's surprising how little new code was necessary for it -- mostly a little refactor of the existing SQL implementation to make it more reusable and of course a lot of tests -- written with the help of dawehner, thanks! There are a few big issues left: split the entity controller into a CRUD controller and the real controller. Once users become EntityNG, roles need to use the existing entity reference item. Same for taxonomy terms and their hierarchy.