Only difference to the 1st generation S-AFC is the extra Purple wire for the knock sensor. You tap that into Pin 57.
Now, how you use this knock feature is beyond me, as I have yet to see a manual, other than in Japanese, and I can't figure it out in my coconut.
The new unit is sweet though, very cool looking, with a few different monitoring options and an extra TF&TF style screen monitoring screen.
The only thing I didn't like about it is the way you navigate through the screens with the joystick, it's super sensitive and does about a million things so you can jump all over the place if you're not careful.
All the same, I might get one when the prices drop a bit, and better info (in English)is available on them, to help tune it better......