I am using the editor widget to edit feature services that the user can add at run time. Each time a user adds or subtracts a feature layer from the map, I am setting the EditorWidget.LayerIDs property accordingly. Oddly, there seems to be a bug in the TemplatePicker portion of the widget where when the control switches from 0 to 1 layers, the symbols are missing from the template. When you add a second layer, symbols from both layers show up. Adding more layers the control exhibits expected behavior, as well as when you remove layers. If this is fixed in 2.1, I can wait until release for it.