Rated 3 out of 5 stars
The addon is a bit glitched. If you press 1 or 2 to switch tabs while the cursor is in a text box, it switches tabs instead of inputting 1 or 2 into the text box. This makes it impossible to type 1 or 2 unless you do it in an external application (eg. notepad) and copy-paste to the text box in Firefox.
This addon should not switch tabs using 1/2 shortcut keys while text box is selected.