No, it's impossible for the moment to deliver reliable keybinding-extensions. Firefox has no API for it, so all solutions need to work by injecting a script into each website, and grap keys from this context. And that simply sucks and leads to many problems. They are supposed to work on a solutions, but it likely still needs 6+ months.
Besides that, vimium works well enough under perfect conditions, and is quite mature as it is a port from Chrome. Tridactyl is also promising replacement for Vimperator, but still needs time to grow, because they just started some weeks ago.
Besides that, vimium works well enough under perfect conditions, and is quite mature as it is a port from Chrome. Tridactyl is also promising replacement for Vimperator, but still needs time to grow, because they just started some weeks ago.