We are using 4 encoders and 1 sonar, and I have gotten it to work: You must plug them in this configuration:
#pragma config(Sensor, dgtl1, encRF, sensorQuadEncoder)
#pragma config(Sensor, dgtl3, encRB, sensorQuadEncoder)
#pragma config(Sensor, dgtl5, encLB, sensorQuadEncoder)
#pragma config(Sensor, dgtl7, encLF, sensorQuadEncoder)
#pragma config(Sensor, dgtl9, test, sensorTouch)
#pragma config(Sensor, dgtl10, indicatorLED, sensorLEDtoVCC)
#pragma config(Sensor, dgtl11, ultrasonic, sensorSONAR_inch)
and then add this in your preauton:
SensorType[dgtl3] = sensorNone;
SensorType[dgtl3] = sensorQuadEncoder;