Rated 1 out of 5 stars

Argh, mozilla.org just ate my review. (Edit: and now my line breaks.)

Short version: you can only add new shortcuts. You can't remove or override builtins like ctrl-q.

Rated 3 out of 5 stars

A warning: do not be confused with the keyconfig addon by dorando (http://mozilla.dorando.at/readme.html). This is a completely different addon.

I didn't try this extension. By features It looks useful. If it implements in the future the feature "Importing/exporting settings to a file, compatible with Opera presets", It can to end being a real nice alternative.