I just installed after blowing out my .mozilla dir. Runs great! Your prefs work good although the backspace doesn't work everytime. Might be my machine? Also, not a biggie, firefox icon doesn't show up on the panel/taskbar (5.8 Standard, Xfce). A black gear thingie shows up instead. I restarted X just in case, but same deal.
Another hint with the new pref. Backspace goes back one page in your history. Shift+backspace goes forward again.
Thanks for all your efforts easuter, Mozilla stuff is a tough build at times.