For you guys that are using the GriGri. I know you aren't supposed to use it as a work positioner (the original anyway). DO you back it up with an Autoblock? Have yours ever slipped? I would use it full time on my tether and then rappel with it and not have to have extra gear or do the switchover. And the GriGri2 is cheaper and made for slightly fatter rope? Any downsides for our uses?