This will probably piss people off, but I'm posting in the realism section, so just think about it from that perspective for now.
Great helmets should provide the most head armor and weight the most. Armets and sallets should give high armor, but not as much as great helmets. Great helmets were the heaviest and offered the most protection. They would penalize your vision and head movement the most too.
I'm suggesting that the great helmets switch places with the high-tier non-great helmets, keeping the stats/prices the same, but switching the names and models.
Currently the helmet progression is based on chronological appearance, and not on the actual protection/weight of the helmets. Yes, armets and sallets were designed to glance blows, but the size, weight, and thickness of great helmets exceeds the former's sheer protectiveness.
*edit: Tourney helms should actually have the best armor, which would be good for armor crutcher humiliation haha.