Rated 3 out of 5 stars

Awesome extension! This is from someone who really is a totally blind user of FireFox.
Since the Tab key is honored as a shortcut key, he just lost a star or two from his rating.
Tabbing is ridiculously important to me in Firefox; i can't survive without it since all of my action is done from the keyboard only!

This review is for a previous version of the add-on (1.2.10.2). 

I can understand that using the Tab key as a shortcut might be a bad idea since it could break existing shortcuts, but that is the case for many other key-combinations not involving the Tab key.
Out of the box, the Tab key is not configured as a shortcut. I leave it up to the user to define his own.
So as long a user does not define shortcut key-combinations that conflict with existing ones, there should be no problem.