You’ve hit upon one of the biggest sources of current pain for me. The best advice I can offer at the moment is the have a method that will convert to a generic list if it is not already so that you can be sure of the type you are getting. For 2.0, we are going to put an end to this abstract way and use models to get data serialized into a more understandable format so keep an eye out for developer previews that will come starting around mid next year.