The performance of the closed loop stepper system is better than the open-loop setting. Only the relationship between torque and acceleration is considered. The torque speed curve shows the peak and continuous torque range of the closed loop stepping system and the available torque range of the open loop stepping system. Usually, the actual torque will be converted into acceleration, therefore, the motor with more torque can accelerate the rated load faster. http://www.dtdmotion.com/closed-loop-stepper-system/