What should also have noticed here that we no longer have models, instead we have technologies that increase the maximum values a unit can have and if unit can upgrade to these values it will. This allows us to do really nice things like divide up what would be a single technology that gave in a model in Hearts of Iron 2 in several separate techs. So if we take tanks here as example, you can separately research a tank gun, tank engine, tank armour and tank reliability (just for the record reliability effects the ability for the tank unit to withstand damage on the attack, unreliable tanks tend to break down). How we set these values can give a countries tanks brigades with different values with out the straight jacket of the nation specific unit. Take the early war British heavy tank brigade, well armoured, slow, under gunned and prone to breakdowns. We can create this effect through out technology system, but also giving the player the freedom to steer his country the way he wishes.