Was searching for something today and stumbled upon an old
PCLOS forum post.
I did the upgrade of FF from 8 to 9 this morning. Web pages are loading faster. I prepared this time by editing the 2 addons I had trouble with last time, due to the version change. I just edited them to be valid through version 20.0. That ought to hold me for a year or so.
That was from December, 2011, so I wasn't too far off. A year and two months later, we are at Firefox version 19. I realized it was time to edit the remaining troublesome Firefox addon again and bump the allowable version number up to 40.0. Maybe that will hold me for another year.