Vimperator was even better, and allowed a very smooth operation of most Firefox without using the mouse. Sadly, it was killed by the transition to a new plugin API.

Vimium and other current options lead to quite some friction, as Firefox disables plugins on many scenarios, such as a new empty page.

Hence, you often find yourself in a situation where you have to think whether Vimium is active and you can use Vim-like shortcuts, or you need to fallback to the Firefox UI.