I have read numerous times from German Tank Commanders in books like Stackpole Books, German Tiger Aces and The Combat History of German Tiger Tank Battlion 503 that after initial teething problems that the Tiger 1 was made into a fairley reliable tank. The units even have factory reps assigned to the Bn. maintenace section. Look at how they made numerous road marchs across Russia as a mobile strike force to cool down the various hot spots along the front. In one book a Tiger Commander ( sorry, can't remember his name ) even stated that the west played up on the Tigers unreliabilty, when in fact he was very happy with it.