[Teraswaerto]

Another thing to consider with gold cost vs resource cost is that upkeep is dependant on gold. I will often build Huskarls early on when it's important to raise an army quickly. However, recruiting lots of gold expensive troops every turn isn't a good idea, since the upkeep will choke your economy.

With heavily armored low gold cost troops you can maintain a larger, tougher, army, even though it takes longer to build it up.