I don't remember which one is confluence off the top of my head, but one of the culture modifiers, spread rate, is how fast the culture spreads (there is some debate if this has any affect if hostile culture is in your way). The other affects how fast allegiance changes once culture reaches the planet (0.07% is the default max decrease, 0.14 the default increase).

In theory, both will lead to your planets getting the 10% allegiance bonus a bit faster, though I'd doubt it would be enough to pay for itself in pure economic terms. Keep in mind even your homeworld gives what, 20-25 credits per second? 10% is about 2 credits per second plus some metal and crystal, but that's only going to be earned on your culture center, and other planets won't give anywhere near that much.

Tradeport will make money even with just one trade port, as weird as it sounds. Its just it gets absolutely no multiplier from trade route.

The big thing that leads to trade being so widely use at the expense of other civic options is that is scales infinity. Unless you sabotage a very long trade chain, each trade port will increase you income at least linearly, there is no diminishing returns to negate their payoffs. Culture and refineries on the other hand have limits (the max culture cap at 10% without upgrades, or the 3/4 refineries each resource asteroid can support) that make building multiple of them at a planet less attractive or useless. The only thing culture has going for it is that it can affect multiple planets from one gravity well. Every other culture center you build will give no where near the benefit of the first (unless its in an area so remote that your culture cannot possible reach it).

If you go culture early, this is why you should do it. If you're not trying to force them to leave a captialship behind or forcing them to get culture as well, I'd say after 3 tradeports/culture centers the trade will start to win easily. Going an entire game without trade is probably suicide, it just can't scale well enough to provide the raw income trade does mid game, let alone late game.

I'm a bit sketical.  The time it take allegiance to actually increase is as much of an issue for culture's benefits as the spread time.  Not to mention that in the big scheme of things it really doesn't take all that long for culture tos pread through your territory with zero culture upgrade techs.

But let's do a cost benefit analysis:

With confluence culture spread 60% faster, which means it takes 62.5% as long for culture to reach each planet besides the origin point of the culture.

Let's say that normally It would have taken 15 minutes to fully spread your culture.  Frankly if you choose one of your more central planets for a culture generater you can probably have culture at 2/3 of your planets in half that time easy.  We won't even consider the time it takes allegiance to go up for simplicities' sake.  This means With confluence all planets are reached in roughly 9.4 minutes and 2/3 are reached in 4.6 minutes.

So the total extra economic yield of confluence+zealous worship is less then 2.9 extra minutes of +10% allegiance for e/3 of planets and 5.6 minutes of +10% allegiance for 1/3 of planet.  I say less then because I used rough breakpoints for this estimate- SOME planets are going to have culture well before the 2/3 break point(for example the source of the culture starts gaining allegiance immediately).  This is simply an upper bound on the economic benefits of confluence.  so 5.6 minutes for 1/3 & 2.9 minutes for 2/3 results in an average of 3.8 extra minutes of +10% allegiance.  Again remember this is just an estimate.

For most of your planets that 10% extra allegiance will mean something like a 10-12% increase in resource production & taxes(for planet with base allegiances of 80-100% as are common early game) .  Let's assume about 11% on average.  So Confluence+zealous worship provide a 11% economy boost for an extra 3.8 minutes.

But here's the problem:  Researching Zealous Worships & Confluence Costs 2600 credits.  In those 3.8 minutes at +11% output the total extra resources product is 3.8*.11*60*100=2508% of your resources gained per second.

To pay back 2600 credits with 2508% of your credits/sec you would need an economy capable of providing 103.7 credits per second- which an early game economy will not have.

Moreover remember that this was an upper bound- Honestly the actually yield would probably be lower and thus an even larger economy would be necessary for Confluence to even pay for it's self, much less serve as an alternative to trade ports.  

Not to mention If you really want to spread culture fast you could just build 2 temples on opposite sides of your empire, then scrap one once you've spread culture to use the logistics for something else.

 Building an extra temple of communion more then doubles the rate at which you spread culture(twice as much culture production and spreading from 2 points, which is better due to culture decay rate).  And frankly building and scrapping an extra culture building costs less then half as much as researching confluence and is a technique available to every faction.

Though while I doubt confluence will ever be a real economic tech without adding secondary effects, this discussion does highlight one of Confluence's biggest problems: It's too damned expensive.  Between researching it and building a temple you've dropped about 4k credits on culture.  Spend that much on culture early game and human players will roll right over your with their superior fleets or economies.

Thanks for the replies - they've shed some light. Keep in mind, I'm not talking about this as any kind of true alternative to trade ports - I'm just interested in its economic benefits for the AL early game - long term trade ports are clearly superior.

Bilun, your point about spending too much on culture early and getting rolled by superior fleets caught my attention though. It's obviously going to take some judgement, scouting, timing, and basically juggling when to get it vs. fleet. There are timings in the game where you've got more than you can possibly spend and timings where you're totally strapped for income. I think using this tech is about finding that sweet spot where you can defend yourself, have some planets colonized and can then invest in it early enough to take advantage of the returns, to help a little to propel yourself. Worth experimenting some more with...

I pretty much agree with Seleuceia. If you're not under too much pressure getting one culture center near the center of your Empire can be a good investment. What I think needs to be tested is putting one on your Empire's border a worthwhile distraction for your enemy, as here is where Confluence would have the biggest impact. If someone really wants to they could test how much faster it boosts your allegiance as well; if the net gain is in the ballpark of 600 credits for say a 4 planet empire, it might have a use.