BTW, a few years later when my family lived in Germany, sometimes you could see the Luftwaffe hedgehopping across the countryside. It was awesome to watch. The cold war was at its height, and flying low was how one evaded enemy radar. The Luftwaffe wanted to be well trained and ready, and the hedgehopping also let the Soviets know they were ready and able.
They did indeed have problems with people getting killed. That's why the stunt was to be done with models until it was shown it could be done safely.