Originally Posted by
Bear5k
In general, yes, but for good and very specific reasons. Stepper motors are, effectively, constant power devices - though you have to calculate both the power delivered by the shaft AND the back EMF from the inductor to get there. Bigger torque requires a greater magnetic field which requires larger induction. Induction and voltage are what control the shape of the torque curve.
You can have a low torque motor with big inductance and high voltage, but don't get anything flammable near it since it will be dissipating a ton of heat (high resistance) in the process. It is definitely possible to have a low torque motor that loses a lower percentage of its power as RPM climbs, but it will start from a smaller base (lower inductance). It's a "testable hypothesis" as to which motor has more power at high RPM between a bigger motor and a smaller motor, but if there is a big disparity in holding torque, chances are that the bigger motor will still have appreciably more torque at high RPM assuming that both are well-designed and manufactured (the smaller chassis will have trouble with the higher currents used by the larger motor). It's pretty easy to find NEMA34 motors requiring more than 80+ VDC, but a small NEMA17 motor would most likely fry at those kinds of voltages.