Would love to try this, however it seems like the Firefox add-on is not available unfortunately. I've already tried the alternatives (tridactyl, vimium), but did not really like them enough to keep them installed. Seems like with wasavi, you can selectively launch vim interface for a text field whenever you feel like it, which was something I missed with the other solutions (or I haven't looked deep enough back then). Anyone managed to run wasavi on firefox by any chance?