I took the back button of a long time ago. All I have is refresh and the url bar. I use my mouse buttons along with the mouse gestures addon to navigate back and forward.
I tried taking the back button off, but it turns out I really need it: not to click, but as a status indicator. Because I use tabs, the back button shows me at a glance whether or not I'm in the middle of a stack, or if I opened a link from a new tab, etc.
