co-pilot worked for me
Didn't use it very long, but it sure helped me get past hovering. Probably cut months off my learning curve. Its not for everybody. Some people don't like the feel it gives the heli and is down right dangerous when flown at high sensitivity. Higher sensitivity works best IMO when the co-pilot is used as a panic button.
Follow the intructions and be sure to use the required buffer for futaba elevator servos.
Used it with variable sensitivity on a slider to get the feel just right for learning circuits. After that, I simply used the on/off channel as a panic switch. Just use mid to high sensitivity and auto-trim off. When I got into trouble, just flip the switch, and the heli would level itself. Once you've gain your wits about you, flip the switch off and continue to fly.
Keep in mind that the co-pilot will only level the heli. If you use it as a panic switch, be prepare for any sideways momentum and/or collective effect that will continue after you flip the switch.