AllPositioningMethods implies that a blend of satellite and non-satellite based methods are used to acquire the position.
SatellitePositioningMethods implies the user wants high accuracy at the cost of high battery use and time to first fix.
NonSatellitePositioningMethods implies the user wants low battery use and time to first fix at the cost of low accuracy.
AllPositioningMethods is meant to provide low accuracy updates at first and then high accuracy updates once the satellites come in to usage.
At present the Symbian backend only uses one positioning module at a time - from what I can tell this means that the user will received the position from satellite methods or from non-satellite methods but not from both. This is quite heavily built in to the backend, such that fixing it will probably involve a rewrite.
I still need to investigate further to confirm this.