The folly of Fisherian compromises was already realized well after Battle of Jutland. Saying that armor would have reduced speed in WW2 era is generally false. It would have simply resulted in bigger ship and more powerful engines to handle with the increased weight while maintaining design speed.
Interwar treaties limiting displacement somewhat hapered effective design, resulting in many of the "Washington-type cruisers" being rather thinly skinned. Some countries also continued to produce light "scout cruisers" a type of ship made obsolete by aircraft, which too were generally rather light on armor. In some cases, these scout cruisers evolved into properly armored warships, as seen with the Italian Condottiere types.
Generally, these are the only cases where armor was compromised for speed and/or armament during WW2 era on capital ships (destroyers and smaller were always poorly armored). That is, they were not armored against their own main battery as per standard practise. There are also some extreme examples, like the overgunned cruiser sized panzerchiffes or the American 16" gun armed battleships (due to the abnormal power of their 16" shells despite their caliber).
All surviving "true" battlecruisers, Renown and Kongo class' were taken in and up armored during interwar era. Though they were still not armored against their own guns.
Carrier design followed different philosophies and for example merchant ship conversions could not usually be properly armored and usually were not very fast either.
Scharnhorst class was a particularily heavily armored vessel, with some 14" of belt. It was also a class wasted (cost-efficiency-wise) on it's role as convoy raider, even the panzerschiffes were. It did have impact on tying up British BB resources, but one would wager that a large precentage of them would have been kept with home fleet anyway, rather than being sent somewhere that mattered (like Pacific). An effective light cruiser fleet, ala WW1, would most likely have been much more effective convoy raiding force.
Scharnhorst was also classed as battleship by Germans, it wasn't really a battlecruiser, as much as a small BB.
You are right in praising the successes of German radar FC in early war. Germans were sometimes hitting with their first salvos, which would have been hard without radar. In fact, the 24km (26k yard) hit on Glorious is possibly the longest ship-to-ship artillery hit ever scored. Which is why I think that around 24-26kms should be the max effective gunnery range for ships in HoI3, instead of the HoI2 system where battleships constantly positioned themselves to fire over the horizon.