Armor choices, destroyer designs, and an abstract naval model

Should Sweden choose an anti-aircraft layout, an internal armor belt, or an external armor belt?

The base naval system treats these options as flat statistical upgrades.

Sweden's naval upgrade choices include anti-air fittings and internal or external armor belts. In the base game, these detailed-sounding options are flat statistical upgrades. The armor-layout terminology therefore carries less detail than it appears to offer. A separate proposal is to develop destroyer templates that another country can buy using civilian factories.