Civilization – Civ V bug in Linux – Free Thought policy is not available when it should

You get a -50% penalty if you are using a unit that requires a strategic resource, and then go negative in that resource.

That is, you lose a source of Iron that puts you below 0 Iron, all units that use Iron will have a -50% penalty until you get more iron or lose some units.

This is especially annoying with Aluminum and Uranium if you have puppet cities that use those for buildings. If you get in a war and temporarily go negative, all of your nice units become expensive rubble.

As per your original question:

I ignore musketmen in general. It's not worth the switch if I can have a unit with more base defense. that, and it's a pretty easy jump into rifling at that point.

The point of the musketmen is in situations where you've got no iron available but need units. They'll do in a pinch, since horse-based units are easily countered with cheap pikes or spearmen.

The french and the americans have unique units instead of musketmen, so they are more likely worth it.

• You get some turns of anarchy, which means your science, commerce and culture stagnates and you get a big penalty for production,
• You lose the policies in the branch you abandoned (no refunds).

Actually I think in some cases it still might be not such a bad idea to do that. Especially if you didn't invest too much in that policy and you are not going for cultural victory anyway. Some early game policies matter much less in the late game. For example you can use a bit of Liberty for early expansion and then abandon it for Autocracy.