Hi,
yes steppers have prodigous torque at low speed but run out of puff at speed, whereas servos just carry on right up to rated, and sometimes beyond rated speed.

My experience is that servos outperform steppers hands down. What we tend to overlook is that a stepper, even the merest hint of torque overload and it misses steps or stalls
whereas a servo just digs into it's 3 or 4 fold overload torque. While you can't rely for long periods of time on that overload it certainly close the gap between steppers and
servos.

I've seen manufacturers of closed loop steppers say 'more power, more speed, never misses steps'....all pure BS.If an open loop stepper loses torque at speed the so does a
closed loop stepper, nor does closing the loop make it go any faster. If it misses a step, that means its marginally overloaded, the drive will insert an extra step to catch up, but
guess what.... the extra step is just as likely to be missed as a regular step, the motor is marginally overloaded after all.

Any motor, servo or stepper will lag if its overloaded, its just that servos have SO MUCH MORE overload capacity and seem therefore to perform much better
that the specs would suggest.

Craig