I've heard it said that some Chinese styles break the palm down into as many as 13 different striking surfaces--e.g., center, cupped (as for ears), the fleshy pad below the thumb, the lower edge near the wrist on the pinky finger side, etc. How many truly different palm strikes do people feel there are?
I have been in a few scraps and also did some Western Boxing, and I can definitely appreciate using open hand strikes over a clenched fist. Certain styles like Baguazhang and Systema emphasize the use of open hand strikes. IMHO, they are on to something.