How about a partial export? Rated 3 out of 5 stars
How about a partial export? Prefs.js includes *everything*, and you may not want to clone your whole Firefox config. You're more likely to have specific config options you wish to apply to others profiles.
The best way I can think of is exporting the desired settings to a user.js file. If a user.js file exists in the profile directory, it will be read, and setting in it will override those in prefs.js Since prefs.js is created and maintained by the browser, manual editing isn't recommended.
I used this trick under FF2, as I had multiple FF profiles customized for different purposes but wanted all to share the same bookmarks file. A one-line users.js file with the appropriate value for browser.bookmarks.file dropped into each profile directory did the trick. (FF3 removed that preference, so I had to come up with a different approach.)
Then, How about using FEBE http://softwarebychuck.com/febe/febe70.html ?
See also: https://bitbucket.org/cat_in_136/configuration-mania/issue/26/export-please