1.) Currently only server side rendered errors are being used for error validation. Even this is problematic as the current implementation directly conflicts with more mature validation frameworks like ember-validations
2.) ember-data should follow the lead of EPF and rely on the user to decide how a failing promise should be handled rather than inject the returning JOSN errors into the errors property. See #6 http://codebrief.com/2013/07/10-things-you-can-do-with-epf/
3.) This would necessitate removal of the isValid state from ember-data’s stateManager. Again, this could be a state that an external library could add.