Here's a fun video on Zeiss optics. The Soviets had old Zeiss equipment and could make better glass for their T-34 but figured why bother? Lifespan of a T-34 tank was short and the emphasis was on numbers. Can't post video so I hotlinked it instead. A good follow up read on how to use the tank sight is the book Panzer Gunner.
One thing they got wrong in that video is how various tank crews were trained to fight. It is mentioned several times that US optics had a narrower field of view. This is true. What was missed was the gunsight was secondary in engagement to using a simple blade sight and the much wider field of view periscope the gunner was provided on US tanks of that era. This simple addition to US tanks allowed the gunner to rapidly slew the turret onto a target and align the gun sufficiently to usually get a first round hit on an enemy tank at ranges of 500 to 700 yards. The telescopic gunsight could be used for subsequent rounds as the gun was now laid with enough accuracy to allow the gunner to instantly switch sights and continue to aim and fire uninterrupted. The German and Russian use of just a telescopic gunsight alone meant it took them longer to acquire a target and get a first round off. Since who put a round on target first--whether it damaged or destroyed the enemy tank or not--usually was the crew that won the engagement.
What page of Hunnicutt did you read about the Sherman's front sight blade? What about the rear sight? I know the Sherman's turret rotated faster b/c it was powered. Here's a neat page about the Sherman sights. If nothing else, check out the porcupine hatches (spikes added probably to deter Japanese infantry). Aiming guns | The Sherman Tank Site