It would be great if we could make a Task be a Subtask when it is in a different Space (and vice-versa).

For example, you take Task 1 in Space A and make it a Subtask of Task 2 in Space B.

When you open Space A, it is a Task. When you open Space B, it is a Subtask.

This would be useful for building a Goals system, where you have a Goal that is a Task in Space A, broken down in to Subtasks underneath it.

But then you want that Goal to be a Sub-Goal of a main Goal in Space B.

This is not possible to do right now. You have to create a lot of duplicates to get this kind of functionality.