I created an example demonstrating what I am trying to do.
I have a DefineList of items that are returned as a Promise but they never seem to render.  I also have a rawItems list that is updated at the same time (to show the difference) and that does render as one would expect.
Am I expecting too much from the binding? 
Or am I doing something incorrectly?
In the interim I am populating a “real” list when the promise resolves and then rendering from there (a la the “rawItems”).