If there's only one Setup, "Open Setup" could skip the picker.
Updating a Setup could be streamlined by tracking the Setup loaded and starting the dialog out on "Update existing Setup" with it pre-selected. (If no Setup was loaded, still default to "Create new Setup", of course).
Maybe move "Change Setups" from the Settings page to an Edit (Pencil?) button between "Open Setup" and the "Reveal config file ..." button.
Some ideas for streamlining Setups: