A remark to user Dave Dockery Rated 5 out of 5 stars
Dave, if I was the author of this add-on, I'd be delighted to read your comment, assuming it would suppose you are already using DuckDuckGo as your default search engine here with Firefox.
Indeed, if DuckDuckGo is the default search engine, this add-on is less pertinent, even if IMO it still is useful, with direct access to major !Bangs, with instant first definition when applicable of a highlighted word with the right-click menu.
If DuckDuckGo is not the default search engine, then this add-on develops its full potential, by adding to above mentioned display of DuckDuckGo's 0-click box on Google and Bing search results page, along with link to DuckDuckGo's own full result page.
I see nothing but sense.