I really like the function, but I think I'll be missing the favicons. I believe favicons should be left as is, and WOT should be separated into a different setting, so that we can have both icons.

The title says it: Duck Duck Go should be added as an alternative to Google at AlternativeTo.net.

I suggest you to remove extra whitespace, newlines, comments(!), etc. from the Lite and HTML versions' code (like you did with the 'main' version) to reduce its size significantly.

Are links like "http://duckduckgo.com/?q=search&t=referer" and "http://duckduckgo.com/Search?t=referer" correct?

Purple color of the links is not very nice.

For example, if I wrote !so into search box, it would redirect me to stackoverflow.com, not stackoverflow.com/search?q=.

Sometimes it is annoying that you have to wait for the results to load...