1. Start blender.
2. Modify a modal keymap in some way.
3. Export the key config.
4. Import the key config.
5. Save as default settings.
6. Quit blender.
7. Start blender.
8. The modal changes aren't loaded. The console has a "No property values defined" error.
A note for clarity: You CAN get changes to modal keymaps to work; you have to re-import the keyconfig every time you open a .blend file.