I went through all of these frustrations as well, sent nasty notes to GM, etc. Having said that it CAN be made to work if you understand:
1. The system engages based on the last brake pressure used. So if you come to a fast stop or mash the brake pedal for any reason it will maintain that pressure and you WILL stall.
2. The "remembered" brake pressure can be reset by putting the trans in neutral, releasing clutch, reengaging clutch while using just enough brake pressure to hold the car.
So, get in the habit of stop - neutral - reduce brake pressure - put back in gear.
Now I can live with it but it should be DRIVER optional.