Good Stuff M07.
I worked my way to era 3 and had a lot of fun.
I got annoyed though with 2 things.
The first one I know has been said before, which is the colony requirements for eras.
I really liike the era requirements as it really makes you develop your colonies, but it is frustrating when it starts limiting your expansion as anything you build needs 10-15 extra people (defenders and residents) when all you want it to be is a plantation. I know in another thread you discussed changing it to be a global pop instead of per colony goals.
Another possibility might be instead to have those era goals only effect the 'min number of colonies' So for example you need to have at least 4 colonies that have 16 pop and 5 defenders (or whatever) but any colonies after you have 4 developed cities, don't have to meet those requirements. This way you keep the feeling of having to develop a presence/infrastructure/administration in the colonies to advance (which i actually really like), but you are not locked into a state of forced non expansion because developing another 8 soldiers and colony slots for 16 pop would take too long, etc.
I had lots of sites ready to go with farms and produce all waiting to accept a brand new colony, put i just had no motivation to pull the trigger, because of the requirements.
The Second problem is one that i cannot figure out why it happened.
I wanted a silver mine so that I could be rich, but the only one i could find was in a spanish zone of control. I founded next to it and my colony immediately vanished along with my expert silver miner. Ok Spain if that is how it is then War it is! I took the colony that was controlling the area, and went to found my new colonial silver mine, but when I founded it it would not give me zone of control over those two silver mountains!
When I looked in the tile exchange screen, both had black 'blocked' markers (so did the tile where my colony was founded) I could never figure out why though as the tiles were between my two colonies and I have expanded borders all around them. Suffice to say my ambitions thwarted I was sad.. I could not build a new colony at a different silver site because of era requirements, so my dreams of being a silver baron were at an end...
Other than that, great job. The Economic changes were interesting. I also really like the indicators telling me which cities were not meeting the era requirements it made keeping track of them much easier!