I have been using Evernote for many years and use it for many different contexts of life. I find that it slows me down greatly to pick a notebook to add notes and to limit my search in. I end up searching across the whole system and I end up saving notes in the default directory. This makes it tempting to look at other products for specific organizational needs.
I think a solution could be a home screen widget that helps to focus the environment on a specific stack. You currently have a home screen widget for notebooks, but this does not help me get to the right place quickly.
Made a very crude mockup:
This widget would be for a specific stack.
I could search across all or any of the notebooks.
I have a button next to each notebook for adding a new note.
My searches are saved
As a bonus, give me an enumeration of all tags used in that stack so that I could one click search by tag.