I'm using Firefox 39. I have to, in able to use 1Password.
If I go to a newer version of Firefox, I would have to go to a newer version of 1Password. To go to a newer version of 1Password, I would need a newer operating system. To go to a newer operating system, I would need to buy a new computer.
Wait...can I run 10.7? Should I consider that?
If it gets around the problems cited, why not? As far as I can tell, Lion is still available; it's ultimate version is 10.7.5.
Addendum: I just now noticed that this discussion is being carried on in the "Ad blocking used to work" thread. Carry on.