Trying Interrupts and Other Ideas...

from pysabertooth import Sabertooth
from time import sleep
import Adafruit_BBIO.GPIO as GPIO
import MotorBridge

saber = Sabertooth('/dev/ttyS2', baudrate=9600, address=128, timeout=0.1)

LED  = "P8_28"
Stop = "P8_29"

GPIO.setup(LED, GPIO.OUT)
GPIO.setup(Stop, GPIO.IN)
motor  = MotorBridge.MotorBridgeCape()
MotorB = motor.StepperMotorBInit()

try:
    while True:
        if GPIO.input(LED):
            GPIO.wait_for_edge(Stop, GPIO.RISING)
            sleep(0.5)
            saber.drive(1, 25)
            sleep(5)
            saber.drive(1, -25)
            sleep(5)
            GPIO.output(LED, GPIO.LOW)
            sleep(2)
            GPIO.output(LED, GPIO.HIGH)
            sleep(4)
        #saber.stop()
        elif GPIO.wait_for_edge(Stop, GPIO.FALLING):
            sleep(0.5)
            saber.drive(1, 50)
            sleep(5)
            saber.drive(1, -50)
            sleep(5)
        elif GPIO.wait_for_edge(Stop, GPIO.RISING):
            sleep(0.5)
            MotorB
            motor.StepperMotorBMove(0, 1000)
        else:
            MotorB
            motor.StepperMotorBMove(2000, 1000)
            sleep(2)
            motor.StepperMotorBMove(-2000, 1000)
            sleep(4)

except KeyboardInterrupt:
    print("Hey!")