I thoroughly enjoyed the great detail and comprehensive background.
Allow me to make one comment (which I cannot stop myself from making): The German "B-Uhr" is short for Beobachtungsuhr or observation watch in English, which as you write refers to its role in navigation. Hence the watch was issued to the navigator, not the pilot when the crew were sent out on their bombing or reconnaissance missions. Pilots wore smaller wrist watches much like the British Mark XI of later vintage. So the Big Pilot is pure marketing - it is a Big Navigator if it has to be described as anything big. The German Grosse Flieger is somewhat truer to the original since fliegen means to fly and both pilot and navigator flew, of course.
Cheers, Dirk