A couple of years ago we had a nice fella get killed on a John Deere zero-turn close by here. His kids bought him a brand new zero-turn for his retirement and the first time he used it he thought he could go down in the ditches like he had been with his lawn tractor.... rolled over and broke his neck.
I don't consider myself to be excessively stupid but I just don't get why a zero turn takes off so badly going downhill but can climb almost anything going forward.... and why the Zero Turns with automotive type steering seem to be able to do most anything much better than a stick unit.