We always play with it. I think it improves the game -- it, effectively, adds more money in to the trade system, and gives more incentives to trade, especially early in the game. It also gives another focus for conflict.
I agree with Charles, though we usually do not play with it. I liked it when I did.
But I'm not confident about balance changes it makes. I agree the bronze city would be especially powerful if not in a contested area.
Thanks for the input.
I have a follow on question: Does this variant work like Mining in that it cannot extend the total value of any Commodity beyond that as printed on its card OR do you get a "virtual" additional card e.g there are 5 Silver cards and assuming you hold the 5 AND New Carthage, would you be able to trade for 6 (value=216) or are you limited to a trade of 5 (value=150)?
This was not clear in rules - it gave an example whereby Salt was increased from 3 to 4 cards but since there are 9 in the deck it doesn't address "going over the limit".
I'm guessing that the same limit applies as in Mining but wanted to ask.
That is how I believe we used it (like mining, not exceeding the normal max), but I'm not 100% certain.