One of our Pilots has been un-lucky enough to suffer two tail rotor problems in the last 4 years. One was a failure in the hover following FOD intake the second a pedal jammed on full deflection. He was fortunate enough to walk away from both; the second incident didn't even damage the A/C.
We teach tail rotor problems all the time as it is as important as engine failure drills if not more so. I have to say I don't want either but given the choice I’d prefer the donkey to stop over a tail rotor problem.
As mentioned here already should the TR gearbox rip itself off that mass of metal on the longest arm on the A/C can put you well out of CofG limits and loss of control is the result. Should you react to the pitch down moment with aft cyclic you will only chop of more of the tail boom which will do nothing to help the situation.
As an aside there was a thread on here a while ago on would you land with a chip light or carry on to your destination. The more experienced pilots who have been used to many spurious warning lights over the years seemed to favor the carry on option. In light of the above paragraph I always choose to land. the physical lose of the T/R gearbox which can follow a seizure normally has only one drill for the pilot to follow and it involves putting his head between his legs and kissing his a**e goodbye.
Another consideration is how many engines the A/C has and are you the only pilot or flying multi crew. In most singles the throttle is on the lever and you can control the rate of yaw and "steer" during a run on landing. Failure in the hover allows you to close throttle and take needed action. If however you are flying twins most have a quadrant in the roof which makes power control during run on landings un-workable unless you have two crew who have practiced for such a situation. Does anyone train for this?
Remember also the engine and main rotor RPM considerations if you lost tail rotor drive as all that drag is lifted from the system. If this happens in the hover and you fail to react quickly you will not just be carrying out a spinning tail rotor failure from low hover but will probably find yourself at some height due to the increase in main rotor RPM. This happened to a gazelle a few years ago and the climb to height was impressive due to the throttle being in the roof and the pilot unable to close it quickly.
With PPL students to save them from having to think when under the pressure of a run on landing we teach the simple trick of steering with your little finger. While holding the lever uncurl your little finger and point it at the floor of the AC. now which ever way you want the A/C to point as you run over the ground point your little finger in that direction. No good if the rotors are French but then they seem to place the throttle where you can't use it anyway i.e. single squirrel and gazelle.
All in all I just hope the little thing at the back keeps spinning fine for the rest of my flying.