Hereditary Rule to Representation costs us 6 GPT more (56-62)
Vassalage wuuld have cost us 4 more than Bureaucracy (before discounting units costs) (56-60), but we remain at Bureaucracy
Serfdom is as cheap as barbarism, but Caste System would have cost us 6 gpt more. (56-62). But we remain at Serfdom (56)
Organized Religion cost us 10 GPT more than Paganism (56-66)
The total cost in civics, with the revolution, costs us: 72 GPT, which is 16 GPT more than what we have today.
Since we are researching guilds and banking, and we are to build several courthouses, markets, grocers and banks 25 % faster, I see the Organized Religion as an investment. As you see, Serfdom is entirely smart and uncontroversial compared to "Caste System".
Finally, Vassalage is not that much more expensive to Bureaucracy, as you see, and with discounted units costs, as we are to reach 20 or so there next turnchat, 15 free units would have been nice.