Kirky, the "deadly" comment is off the wall, but the palm heel strike is powerful because you are using a part of the hand that will align with your arm automatically. You don't have to worry about your wrist flexing. The obvious downside is that you are more limited in the targets you should strike. As hedkikr said, you aren't going to break knuckles on a hard surface, but you are less likely to penetrate a specific target.