I do not use them but I would go for normal manual lockers just because you have much more control. An auto locker may lock up on a hill you have to turn on which you would off left the front locker turned off for example.
They can also be a bit harsh on the running gear as the lock while wheels are spinning.
I would definatelly save up a bit more cash and go for a manual air locker. This way you will also have a compressor in your vehicle
