Sync / back up Chrome extensions' configuration for re-use

I've had measurable success with simply copy and pasting the chrome-extension_<extID>_0.localstorage and chrome-extension_<extID>_0.localstorage-journal files found at

Windows NT5:   %userProfile%\Local Settings\Application Data\Google\Chrome\User Data\Default\Local Storage\
Windows NT6:   %localAppData%\Google\Chrome\User Data\Default\Local Storage\
OS X:          ~/Library/Application Support/Google/Chrome/Default/Local Storage/
Ubuntu:        ~/.config/google-chrome/Default/Local Storage/

from system to system, but, as it depends how the developer has chosen to store the configuration, it doesn't work 100% of the time.