I have tried switching to the newer version of FF but have found that I just can't live without Chrome's built-in "Translate to English" feature. I realize that this probably isn't that important to most users, but for me it's something that I use almost daily. I checked briefly for FF plugins that offered the same functionality, but quickly got the sense that nothing was going to match the quality of Chrome's implementation, so I switched back to Chrome as my default browser.
Has anyone found a worthy replacement for Chrome's translation feature in FF?