Great thread cite Geronimo. Makes me want to go practice. Like here on THR they like to keep people honest. Like that little hint from the antagonist about his stint with Blackwater.
I've tested myself with convulsive grip down to what I call my golf grip, which is equivelent to sqeezing a tube of toothpaste for a golf club. You want to hold it tight enough so that you don't lose it in swing, but not too tight that you squeeze out the toothpaste. I haven't timed myself, but regarding accuracy, I find that I am generally more accurate at around 75%. For faster shots, I increase my grip strength up to convulsive, which I define as gripping the gun till my hand shakes and then backing off just enough so that it doesn't shake anymore. The problem for me (which could be worked out with strength/endurance hand drills) is that with a convulsive grip, my hand fatigues fast and starts to hurt. This, however, is not an easy solution because of arthritis in my fingers.
Generally, the recoil was a tad less when using a stronger grip. Also, so as to compensate for hand fatigue and to improve control, I tried increasing grip strengh on the weak hand instead of the shooting hand, while wrapping the weak hand around more of the shooting hand. This works better for me.
At the end of the day, I still can't shoot nearly as well at speed as the guys on the thread cited to by Geronimo, but with practice, who knows.