Rated 4 out of 5 stars
good to go so far - can test here...
maybe needs a toolbar button to toggle state?
i miss another ext which, in addition to the referrer, could also spoof the UA. would be nice to see a more comprehensive header manipulation tool that worked on a per-domain basis
About the state toggling: I made the extension restartless, so you can use the already present functionality in the add-on manager.
It will be there as soon as the new version is reviewed.