Yeah, I don't think I like this change. I don't understand the logic of having an SP give the ability to buy some special new unit when one can already buy just about any unit already through normal game mechanics, so what's the point?
They're extremely cheap.
Also, with only one more policy in the Commerce tree, you can even reduce the cost further so that they're cheaper than warriors! (Standard = 160g)
If that wasn't enough, they also pillage without expending movement points, get double the gold from plundering a city, and they can charge into battle the very turn you buy them. Oh, and they have the bonus vs. mounted units that the regular pikemen have too.
They can easily pay for their initial cost through their abilities. (Though, don't forget, maintenance costs are still adding up on them.)
Also, all you need is a single city near the enemy and you can have landsknechts swarming out of it like a beehive in a single turn.
Even if they start to get relatively weaker from enemy tech advances, they're still useful as kamikaze troops to wreak destruction, create blocks, and to soak up enemy attacks.
If you happen to have a lot horses, you can also have an army of lancers once you tech to it. Though, I prefer to send most of them out to die in combat if I have a lot and I only upgrade a few. Due to the landsknechts cheap cost, you'll have to pay much more gold to make up the production cost difference between landsknechts and lancers. Though, they're instant gold troops, so you should always have just as much as you need anyway and buy them on demand.
I used them in my Portugal game with great success. With my fat trade routes and religion, I was raking in gold, and zerged my neighbors out of nowhere.

I played relatively peaceful before that while building my fortune and had a slightly below average military. So, be wary during this time period if you see any Commerce civs with a heap of gold!
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The only complaint I have against landsknechts is that they make that silly swinging weapons noise way too much. It sounds like I'm watching a cheesy kung fu movie.
