Here's a demo at normal speed:
You can use any blade you want, but tripping the mechanism ruins the blade. You also have to replace the brake. Personally, I'd rather be out about $200 than one of my fingers. The idea is that you never want to have to use this safety feature, but it's there if/when you need it. Kind of like airbags, I suppose.
In that example, it took a pretty big chunk out of the hot dog. It's not losing a finger, but man, that would still be a mess!
I would much rather have the mess lol. I bet my dad would rather have had the mess hat would heal instead of just part of it that he has now.