Using C.Fn-04 on Mark IIN - Action

When shooting action, such as football, I have gone to C.Fn-04 to allow the press of the " * " to do my focusing when pressed and stop focusing when released. I am not sure whether to use setting 1 or setting 3 in this. Do you action photographers find greater success in getting in-focus shots using the "*" button method or setting it to "0" and allowing the shutter release button pressed half-way do the job for you along with AI Servo?

What setting do you use in C.Fn-20 for AI Servo tracking sensitivity for action sports such as football or basketball?

I use CF - 4-1 all the time except when I give the camera to someone else to shoot.

Adrian
I use setting 3, I did find it easier, you can focus on your subject, let go and you did not have to worry about loosing focus if subject moved or a subject ran in between. I shot 98% on manual so I don't use the setting that uses back button to focus and shutter to lock exposer. As far as C.Fn-20 I use I think it is 0 which is standard speed. If you go to this link, I pretty much have it setup with this
http://www.siphoto.com​/?canon1DM2N.inc

Hope this helps