I fully agree with many of the other users. A great enhancement would be to allow sharing of stacks. I don't see where this poses a problem with usability. If I share a stack with someone and they accept it, then they get to see the entire stack and inherit all of the settings I've placed on all the notebooks in it. Similarly, if I accept a stack, then I would accept whatever permissions and settings that stack owner provides.
Ditto here. I just became a premium member and would love to see sharing of stacks. Without it, the product is far less usable. Would also be useful to be able to nest stacks into another hierarchy (perhaps drawer).