I do like to use FireLine over rocks for several reasons. First it is very durable, and can take the punishment. Second, it is so strong, that if the bottom bouncer does get hung up I can often pull hard, break the leader, but save the bottom bouncer. Third, I have more sensitivity because FireLine is no stretch and can often quickly feel the bouncer dragging too hard and lift it up some before snagging.
Good Walleye Fishing