I prefer ESCs that you can disable the cutoff or set it to an absurdly low value on helicopters. You just don't have enough momentum in a heli to want to have the motor cut off without your control.

The best way to calibrate your flights is to use a good charger that will tell you how much charge is going back into the battery, then you can increase or decrease your flight times to get the right discharge. Timing your flights so that you use 80% of the capacity is a good rule of thumb.