Actually the Spear system stuff by Blauer is of great interest to me. A LEO friend of mine turned me on to them a while back. I really like the video you can find on youtube where he talks about the flinch response. In our style we have an exercise called shomenuchi ikkyo undo (don't know how many groups do this movement). My sensei have always been adamant that we train constantly to get the hands up immediately at the sign of anything incoming. I've been taught that it needs to be a basic reflex much like these guys teach it as a basic "flinch" response.
Anyway, all good stuff. Which reminds me that I need to revisit this with my students...
EDIT: Well, I'm slower than Sy here in posting, but very nicely he posted all the links to the various vids I was talking about... So now I won't bother looking them up...