750 Watts or maybe a bit less would be about right for brushed DC and BLDC motors, as is 1200 oz in for steppers. I think the brushed DC servos on my mill are about 500 oz in. I'm running the motors at 80 volts rather than the original 100 volts, and the maximum measured output to the motors 30 volts at 100 IPM. I did this because the stepper runs on a 80 volt power supply, and I wanted to just use one power supply. The Z axis is a 1200 oz in stepper and I cut the torque back on that to about 1/2 power. Normally you are running the motors at a fraction of their rated power, so theoretically you could get away with less power.