In my games, 1 GA has saved me an average of 20 turns of regular culture in either of my legendary cities other than the capital.
as you show yourself...2680 culture/120 cpt is 22 turns
my biggest question is whether free market is worth more than an extra artist in all of my gp farms.
I am sorry to disagree, but that can only be true if you have 2 already legendary cities and a third one very far from legendary and doing only 120cpt. That's never the case when you get 10+ GA.
<<From now on I am talking about a 1200AD finishing game>>
The GA that are not so sorely needed as the one in your example only save 3 turns civ-wise. The GS I used in Liberalism as a test saved me 7 out of 10 turns.
Factors to take into account:
- 7 turns is better than 3 turns but...
- A turn at the end of the game is worth 1.9 turns at 1AD (or 200AD).
- GS means you might switch to Pacifism sooner.
- GS means you start working on Hermitage sooner. 7 turns of Hermitage are some 800c or 0.9 turns at the end of the game.
- No GS means you get more hammers from Bureaucracy.
So the jury is still out. My numbers seem to say that a GS is always slightly better than a GA, I'll try to prove it with a 3GS game. My numbers come from this hypothesis:
240-180-100 cpt in FS in 1AD
500-280-120 cpt in 1200AD
WastingTime, please, would you be so kind as to present your cpt figures just after revolting to FS and at the end of the game? Different numbers could mean a lot of a difference.