It does eliminate banding and minimizes noise because
- the M8 uses a two-stage analog DC amplifier to increase the sensor signal levels when ISO is above base ISO; at ISO 160 the low-gain stage is used; at higher ISOs (800 if memory serves) the camera switches to its high-gain amplifier
- with this method the part of the signal responsible for the banding (a.k.a. the artifacts) is not amplified to the point where it is digitized; similarly the read noise level is lower as well
However this useful technique is limited to a three stop 'push'.
In general newer technologies have lower artifact levels which only become digitized at much higher ISO amplifications.
At some point the signal from all sensors can be amplified to a level where artifact components become digitized. This is the reason some brands switch to digital multiplication to increase the signal (and noise levels) or a hybrid of digital and electronic methods at higher ISO settings.