Very good Post TaiChiBob,
Yes, I would say that when you are in a situation of having to defend yourself against a knife attack you must already have done all you could to not be in that situation, meaning you are now literally defending for your life. In this situation anyone who has any martial training is already better of than someone with none, meaning your reflexes should be better and you panic less.
To come to Black Jack's question, (stating direct) I would say (I'm thinking what comes to mind):
_ When implementing defensive techniques, focus on simultanious stepping out of direction of attack (when attacker uses frontal attack) with blocking on elbow to avoid contact with knife. Grabs and Chin Na should only be attempted when you are safely out of the attackers comfort area.
_ Techniques like trapping hands and sidesteps would be the safest to "line the attacker up" for your attack or Chin Na.
_ Mostly avoid getting close while the attacker still has control of the weapon, and do not try to kick the knife out of his hands: The first reaction would be to turn the blade towards your foot because he will cover for his face with other hand.
This is just what I think, would like to hear some comments. Mostly If you are facing a skilled knife fighter, your chances are better than none. I cant really say anything for certain, haven't been in that situation
"If we dont worry then nothing shall worry us, only then shall we be of sound mind"