Rated 5 out of 5 stars

I must be confused. I have this functionality already. Open search engines drop-down. Go to 'manage search engines.' Assign a letter or keyword to your favorite searches.

To use, simply type "i" (or whatever) search term and I get results from ixquick. Or duck-duck. Or anything else.

So if I'm wrong, and Mozilla has removed this ability from their latest abortion of a browser, I apologize.

This review is for a previous version of the add-on (1.1.6). 

That's not the function this replaces. This add-on adds back the ability to have a separate engine for the URL bar, the search in the upper right, the about:home page and the new tab page.