I did a neat little change:
Pop Sac from Slavery to Police State.
+25% military unit production from Police State to Hereditary Rule.
+1 happy per military unit from Hereditary Rule to Slavery.
The result is that BW isn't godly, and early game production is much harder. It is still good: Slavery lets you build mega cities using large armies, and Chopping isn't bad either.
This also makes the "early chop-and-whip" rush to slaughter the AI much harder.