[berkes]

If it is anything like Pentadactyl was, the difference is mainly that Vimium changes very little in Firefox. You, your spouse or your co-worker can still open Firefox and use it, as used to. Yet with pentadactyl, everything is gone: the addressbar, back-button, menu's etc. This might be what you are looking for, though.

That was one reason for me to ditch Pentadactyl (and also vimperator), and use vimium instead. It allows you to keep using Firefox as normal, gradually sliding into the habit of using the keys.

[bovine3dom]

Tridactyl is much less extreme than Pentadactyl, at least out of the box. Probably the "worst" thing we do is override Ctrl-A and Ctrl-F.