I see the GL as a mill-stone around our neck. It is a worthless wonder.
Consider Its' benefits.
1. It gives us every tech known by at least two other nations (that we know) until we have learned Education.
2. It gives 3cpt and eventually 6cpt.
Now consider the penalties.
1. It costs 300 shields to build.
2. It requires the knowledge of an optional tech.
Now you can discuss the ramifications of the contrasting pro's and con's.
1. Between building the GL and learning Education (when it expires) what will we gain. We have two choices. First we can turn research down or off and accumulate gold. This will of course condemn us to not taking a tech lead since 2 civs will already know any tech we get. Since we may not know all the civs, it is likely that there will be civs out there that are even more advanced, on another continent maybe with more civs and better terrain. Thus we can never get a monopoly tech and thus buying "stuff" like maps and resources will take up some of the extra gold we make. Since the upgrade multiplier is 3 for C3C we will not be able to make as many upgrades anyway as we would with "classic" Civ. C3C has a much lower resource density. If we save gold for upgrades and find ourselves without iron or horses then we end up with dozens of warriors about to jump into Republic and everything is a mess. Second, we can try to research at an accelerated rate to get a monopoly tech, or a tech lead for military advantage, in which case the GL will provide no benefit, except for a few initially. Thus we will be 300 shields shy of where we should be, which is 10 horses or swords and enough to take out a neighbour on their own.
2. What are our chances of getting it? Well, right now we have one city. The next city will be a settler factory, and the third city is also potentially a settler factory type city too. That means we need to wait until our fourth before we can begin to build it. Therefore it is not likely that we can complete it before Lit is known by other civs, and therefore with cascades from the Pyramids in particular our chances look slim to none and we end up with an expensive library since we will not be able to cascade the HG or GW ourselves. In trying to build it of course, we cannot reduce the towns population and it will max out. This means higher slider settings just to support 1 town. If the town is not on a river then the pop will max out at 6 and we waste food.
3. Just to finish with the GL. A useful tactic is to acquire the GL to catch up in tech without learning Education - gift the city to the AI and then avoid learning Education for a while (until MT usually) and then capture the city back to catch up in tech. We cannot do this here since we are proposing to handbuild it in our core, and we cannot tolerate a core city being owned by a rival.
So, not only is the GL risky, but is is actually detrimental to our chances of winning the game. It would be like tatooing "I love Britney Spears" across your forehead. Might seem a good idea after a few beers at the Karaoke bar, but you would spend the rest of your life regretting it.
4. Lit is an optional tech. We don't absolutely have to have it. We may choose to have a republic at some time sure. At the moment we have one lux.
With no other luxes and to support republic we would need a slider hike forever, or size 3 towns.
5. Libraries. When will we need libraries. In despotism? Nah.. I don't think so. Therefore we need to prepare for becoming a republic first, before we start building libraries.
6. So from lit we end up with a monopoly tech. Wow. Congrats team.
Mapmaking is similarly foolish right now. This is not an archipelago. The starting landmass is apparently big enough for 3 civs. So it's continents or pangea. If its continents we will probably need suicide galleys for contact or wait for NAvigation/magnetism. So why mapmaking? We can already sail the seas. You don't think we can trade maps at this point do you.
Printing Press is required for that.
You want to sail the high seas with settlers to the corners of the map to plant settlers in every godforsaken nook and cranny? Puh-leeeese!
You want us to build the lighthouse maybe? Obsolete with our UU of course, already have extra water movement of course, only site that could build it will be about number 6 on the city list of course and we don't even know what our landform is yet.
So what does currency give? It gives markets which compliment our commercial trait. It gives us the most expensive monopoly tech we can get. It gives us a tech that the AI neglect. It puts us a step nearer the MA. It prevents the wonder happy citizenry from commiting Hari Kiri (sp?) in the AA.
Vote currency. Vote to win the game.