I have been playing with stepper motors for a while and believe they have lots of uses in radio control models.
They are super smooth and via a controller board (software) you can vary the speed, step from a known position to another very accurately.
The biggest frustration is they have no "position feedback" unlike a servo which has an integral potentiometer which enables position tracking & fairly accurate position reproduction.
Often when using steppers you need to identify a "home" position when you power on and from that point you can control the position accurately by counting steps, but if you experience a power failure the position information is lost and the system needs to be reinitialised - this can lead to a non viable/complex/frustrating solution.
I have recently been using a non contact sensor - you simply locate the sensor near the end of shaft & position a Diametrically Magnetised magnet on the end of the shaft.
The sensor is accurate to at least 1/10th of a degree - possibly more - the manufacturer suggests accurate to 4 decimal places, the sensor has low latency as it can keep track of the position even at an rpm of 100,000
In the event of a power failure as soon as the power is restored you simply read the sensor and have stepper position information
If you want any more information PM me
C-3PO