The 75mm vs the 76mm/dedicated AT guns, that's certainly another whole discussion. The Americans obviously had their doctrine going into the combat and tweaked it on the ground then they needed to, However the US armour's reluctance to take Shermans with more than the 75mm was an outlier in this regard. The understanding from the tanker on the ground I can understand, they are mostly fighting German infantry forces and the 75mm was doing good work. Some desk jockey comes along concerned telling you to take 76mm Shermans that have a lower HE charge, you'd obivously tell him to go to hell.
When researching Arracout I bumped into this first hand. It's right at that point in the campaign that the US Armored Divisions were under pressure to switch over to having a much higher proportion of 76mm Sherman varients. The losses the US sustained in Normandy had the US brass scared of German armour (finally) and were putting the pressure on. The 4th Armored was certainly one of those Divisions opposed and by the time they went into their September operation the whole division only had 20 76mm Shermans scattered across the Division. Working out which Battalions received them is a bit of a logical step by step exercise as the team couldn't find any hard paperwork stating where they went. Abrams's 37th Tank Battlaion probably only had two 76mm Shermans. I understand the 8th lost far more tanks in Normandy and Brittany than the 37th so probably got the most as the September replacements came through. Even after Arracourt, when the 37th Battlaion had fended off a concentrated attack from dozens of Panthers there was still resentment around giving up the 75mm Shermans. Abrams had to be ordered to take a 76mm Sherman to inspire his men to follow suit. Despite this on the ground protest however Zaloga did some digging in the archives and highlights that by the end of the war most of the Armored Divisions did have a serious complement of 76mm Shermans, in some cases out-proportioning the 75mm Shermans available. Realities finally struck home for the tankers on the ground around the time of Bulge. Not to mention The US 2nd Armored getting a pasting at the Battle of Puffendorf in November 1944.
As for the Germans, I think their race to uparmour and up-gun thier Panzer forces was more out of necessity. Limited natural resources that were under threat (Iron from Sweden for instance) would of been a massive concern from the get go. Not to mention the lions share of their commitment was holidng back the Soviet juggernaut... which generally liked building big things in great numbers.
If they didn't beef up their Panzers compared to what they went into Russia with in 1941 it would of been a much shorter war. I don't think they were paying as much attention to the Western Allies when it came to deciding on final design decisions at least in tanks. Armour heading west with Zimmerit coatings when none of the Western Allies used magnetic mines is quick example. The problem with the Germans was they designed to many different versions of vehicles and weapons. Great for wargamers, utter hell for the logistics arms of the Wehrmacht.76mm
