IMO lock it up front and rear. i've got an EZ-locker in my rear end and i don't even notice the thing unless i'm going around corners and hear it clicking usually. you will have to change your driving style a little if you like keeping your tires -- if you can, speed up before you get to a corner and coast around it with the clutch in, it'll let the locker ratchet instead of locking up and scrubbing the tires.
