Rated 4 out of 5 stars

The addon is great... but...
WHY you didn't make it support Firefox < 4?
Yes, I know that FF3.6 and earlier don't support restartless addons (they ALWAYS require restart), but it must be a workaround there to bypass that "protection".
For example, you could make your addon change some Firefox files (it seems that most of the Firefox source code is stored in .js files) so that it does NOT require restart anymore but loads all addons instantly after installation (like Google Chrome does)...
OR you could just make an "addon loader" that would handle all future addon installs/uninstalls and load addons instantly... I bet it is possible.
( If it is possible to block / protect the mozilla:config page and the entire Options dialog (and I have seen some addons that can do that, preventing users to change Firefox configuration) then this is also possible. )

This review is for a previous version of the add-on (5.1-signed.1-signed).