These issues went away some time ago and Firefox now seems as stable on Linux as it is on Windows. I like that the latest Firefox still works on older Linux distros (Ubuntu 8.04), as does Opera - Chrome says 'your OS is unsupported' and refuses to upgrade itself.
I did find that Firefox 8 doesn't properly reload tabs when the new 'only load tabs when selected' feature is turned on (using Windows) so that seems a bit buggy still.