On my Firefox it is the default search engine.

Seriously, I was thinking the same thing a couple of days ago when I downloaded FF Beta 6. Adblock used to be my first installed extension, now DDG SSL search is. Right after that I "fix" the fallback address bar search as well.

I dunno. As an experiment I set my default search to duckduckgo about 3 weeks ago and I'd say I end up running about 30-40% of my searches a second time with the "!g" command to forward to Google instead.