This is definitely a want to have item not a need to have item. I haven't used it for anything I couldn't do before it just went MUCH faster with the flex ruler.
Maybe Because I am a Lefty (28 July 2007)
I hit the button a lot while using the blade causing it to retract while I am using it but that could just operator error. I still prefer to have this knife out vs. traditional for safety when not in use.