I fail to see the point of these "bangs" versus resolving them locally (e.g. using firefox keyword bookmarks -- http://johnbokma.com/firefox/keymarks-explained.html). Specially if you are using DuckDuckGo which I guess it's for privacy reasons (rather than say quality of results), why would one proceed to send them many more queries than they ought to receive?
Just do these redirections locally and send them to the appropriate site directly, skipping yet another unnecessary and potentially-meddling middleman.
Most damning is !g where both DDG and G get to see your query , offering zero privacy benefit and double the risk.