Actually, what Bob teaches is NOT to be used against "purse snatchers." What he teaches is situational awareness (i.e. making sure you never get into a vulnerable situation), and what to do when you're life is in danger, and you have no other choice. Bob was PKA (full contact) middle weight world champion for 9 years, and retired when his wife was attacked and nearly murdered in a parking lot. Once he nursed her back to health, he began working with her on "last line of defense" techniques. Nearly all of what he teaches is close quarter, grappling techniques, most of which will cause permanent damage and some even death. One example is keeping your car keys in your fist in such a way to allow gouging someone in the eyes with your keys, blinding them. Again, these are things that would only be used when you feel your life is in danger already, and there's no other chance of getting out of it.
There's no guarantee that his techniques will work, but then there's no guarantee that having a CCW will protect you either.
Mark
You can stick to your car keys I guess, I will rely on my .357 snub nose.