None of the 4+ versions work for me.
I am using FF Beta(with e10s enabled) and version 3.5.23 works fine except the secondary accounts open the main account(if i disable e10s it works as it should).

I tried a number of times to move to 4.0.1 and now to 4.0.2,but every time it just wont work at all.
Not even my Yahoo and Gmail accounts are working.I don't know what is up with version 4+, but it just won't work for me no matter what.

As another review said - WAS a great addon.

I will stick to 3.5.23 as long as i can and as long as it works.