We use the `Backlog > All` view to see tasks grouped by the iteration they are assigned. All items not assigned to an iteration show up in the "No Value" grouping. From this view, no matter which story you choose, the `Move to...` dialog only allows you to move the selected story to another iteration. If the current story is in an iteration, you cannot move it to the backlog like you can do from the iteration view.
Feature request is for the `Move to...` dialog to show the backlog destination for a story if that story is currently assigned to an iteration.
