Feedforward compensated systems and methods for their use in disturbance rejection in switching power converters and other systems. In one instance, a compensating component receives a sensed output and provides a duty cycle adjustment signal, the duty cycle adjustment signal being obtained from signals indicative of present and past load current variations. In another instance, an adaptive compensating component receives a sensed output and provides an adjustment signal for compensating for load variations. A compensator design component receives the digitized sensed output and of provides compensating component parameters to the adaptive compensating component; the compensator design component including a learning function.