Indeed, the -300 didnt have this nifty little feature. I always wondered why it was never installed. I also wondered how effective this feature is performance-wise. Our -100's had the ground spoilers deactivated, so only the roll spoilers would pop up. Also, the Flight/Taxi switch is magnetically latched to the Taxi position. Once the power levers were advanced above 15.5 PLA (according to my notes, not saying that 12 is wrong) the switch would automatically flip up to the Flight position, incase you forgot to do it manually. Happens pretty regularly if you fly a mixed 100/300 fleet.