microstepping will only give you smoother motion and less noise and will NOT increase accuracy.
A stepper motor has a tolerance of +/-5% of 1.8 deg (on a 1.8 degree motor) per step and this is only on the full step position and microstepping between steps will in most cases not be linear, so dont expect to get good accuracy or repeatability between the full step positions.

Also higher microstepping resolutions will also help to eliminate the zero position glitch that is very prominent with drivers that are limited to lower resolutions or morph to a full step driver after a certain speed.
While this problem will not really effect applications like CNC machines it is a big problem in applications where very smooth motion is required.