In reply to Dave 88:
If the leader falls the strain on the last bit of gear is the same as a normal leader fall, the force goes down and pulls the second up, which should stop the fall. The tibloc/ropeman would cathc the second if they fell, stopping the load from passing to the leader and pulling them down.
Ben, I do similar to you and remember the tricky bits as I pass them, but instead of using an autobloc, try to find a stance or bolt when the second is near and body belay or direct belay them over it.
As I said a few posts ago, there is potential to damage the rope in falling onto ropemen or tiblocs, so I don't do it.