In it's place, I've made the following adjustments:
- Installed the tabbrowser preferences extension, which provides a few single-window tabbrowsing options.
- Installed tab clicking options to allow control over what left- and middle-click actions on tabs and the tabbar do.
- Opened about:config in the address bar, searched for "browser.tabs.loadInBackground" and made sure it was set to "true" to allow middle-clicked links to open in a background tab.
Incidentally, if you haven't already tweaked Firefox to uber speeds, I recommend downloading the tweak network settings extension, which makes Firefox about as fast as Opera. :)
In other news, this is mildly disturbing. Enjoy!