Forgot to mention, there is some rope slip if you're using a prusik that will take up some of the force, but I couldn't tell you if it would be enough to realistically reduce your chance of injury. Too many factors involved to probably be able to calculate reliably.
For me, when I use a rock harness when I'm in a stand, I use one of those elastic inside of webbing tethers that the military uses for the door gunners, along with some hope and prayer. I don't know if any of which will actually save me if I fall. When I'm in my saddle, I just keep my tether tight as much as I can and do my damndest not to be in a position where I'm going to slip.
For me, when I use a rock harness when I'm in a stand, I use one of those elastic inside of webbing tethers that the military uses for the door gunners, along with some hope and prayer. I don't know if any of which will actually save me if I fall. When I'm in my saddle, I just keep my tether tight as much as I can and do my damndest not to be in a position where I'm going to slip.