Hmmm I have had ZERO! issues with Firefox 20,21,22,23 in KDE,Cinnamon,Ubuntu,Funduntu,Bodhi,Xfce Voyager,OpenSuse,Enlightment,Unity and Windows 7. Running older Ati 4350 on dual displays using the default open video drivers.
So general statements like
" I finally had to admit it is too flaky in many environments"
Just doesn't seem to ring true. Of course there are individuals due to hardware or flaky graphics drivers having issues.
But that isn't a Firefox fault. Firefox fault would quickly materialize across multiple hardware and OS platforms.
And would be obvious to all.