samcheetah said:
there are two types of position control; absolute positioning and relative positioning. the stepper motor uses relative positioning. you give the stepper a sequence of steps to move its rotor. at any time you know how many steps you are from some reference. the problem with such a system is establishing the reference and depending on the load the stepper might miss some steps so there might be a situation when you wont know where you actually are.
RC servos use absolute positioning. you always know where you are at any time. RC servos have lots of torque so there is no problem of missing steps as in steppers.
i hope that helps
But if look inside ink jet printer, most (all) manufactures going from stepper motor to servo motor with feedback via zebra line/wheel. HP have always use servomotor from pen-plot time to now, but other manufactory (epson, lexmark) have often very loud and beeping stepper motor solution, but now for high resolution printning needs using servo depend of not can make fine step enough and soft moving in stepp motors compare to dot-distance without patterns in picture - and servo make printer bit more silence...
Is also long time ago harddrives going from stepper motors to voice-coil with servo loop, not only depend of wanted higher maximum speed...
In most case have motors with servo loop much higher resolution and faster response, but also more complicated to design (special for digital and programming people with no 'analog' experience) and needs analyze whole mechanical system to make best possible PID-paramters mm. depend of wanted respons.
(i make coarse calculate for long time ago on servo loop for focusing lens in optical pickup in 8x CD-burner, and find out needs bandwidth around 8 - 10 kHz to follow uneven surface still in focus in full speed, ie lens can vibrate as discant tweeter in loudspeaker, and this loop is pretty hard to make cheap in software, A/D and big crunching DSP, but cheap with OP-amp, couple of resistors and capacitances in analog way _if_ you find out right parameters on whole mechanical system...)