It's now clear to me that the Servotronic is just a speed sensitive option of the hydraulic system. I don't think the US X1 is equipped with the electric steering even in the 35i Xdrive, otherwise it would be noted and marketed as a energy savings measure.
Still not sure why Servotronic is an option, other than the fact that it was a way to cut cost. It's standard on every other US BMW. On the ROW X1, it is an option as well, so maybe some don't feel the need for extra boost at low speed given the X1s relative light weight.