I suppose we have to ask ourselves 'what does trading tech mean?' Is tech trading something you whisper to a foriegn diplomat and he says 'of course! It's so simple!' or perhaps you hand them a few diagrams describing how to build a mine? It's abstractly dealt with, certainly, for the sake of simplicity but if it were not, if perhaps you gave them mining tech and it was a physical thing like a caravan with mining engineers, scrolls and materials that had to get to the friendly territory/settlement you're trading with and can be vulnerable to attack by neutrals. If you share borders it would be instantatious, but in the beginning it's likely they would have a fair distance to travel. That would certainly stagger the rate of tech trading.

If that is too impractical/unworkable perhaps simply have a time lapse between when you send the tech and when it is recieved (and when they send one and you receive it) with the turn lapse dependent on how far away they are from you. In larger games it may not be worth the bother until you get to more research-intensive techs, which would also help the problem of early tech proliferation.

I can see the potential issues but technically tech trading isn't in the game yet. You can go to diplomacy screen and add techs to the trade window but the AI won't accept any trade deals right now regardless of if you have the Diplomacy tech.

As the for the issue I think the simplest solution is to have the research level increase for each tech traded. This would mean someone who trades to gain 3 techs would have his next R&D project level raised by 3 making it a long ways off. So if they really want to specialize it might not be a good thing to trade techs as it will slow down when they can get the next advancement in the area they are specializing along with other future advancements.

Overall though your argument sounds more like a reason against tech trading at all. Because I hear the same kinds of arguments when it comes to Civ games on why Tech trading should be turned off. Empires that start next to each other and trade can effectively cut in 1/2, 1/3, and so on their R&D cost based on how many there are and if they trade techs.

The argument holds true to pretty much all TBS games as tech sharing basically gives you something for nothing. It does not cost you anything to trade techs and you simply gain stuff that would of cost you resources otherwise. The only real potential cost is that your enemy is also getting something for nothing so it's a matter of are you in a good enough position that you both getting something for nothing will help you more then it does them. The answer is almost always yes as not trading techs will often lead to them trading techs else where and then your out the free tech.

 Ty TCores for bringing this up.  It would be nice if the trading technologies were allowed but not like GC2.  Would be better if the technologies traded don't receive benefits immediately via the trade.  Think there should be very strong restrictions on trading in vanilla campaign.  I want them to be allowed but just to have less influence of the overall game than they were in GC2.  Maybe a mechanic where you can only have one technology trade for x amount of turns while your faction is learning the new technology.  Kinda of a stepped process.  Normally researching your factions own tech might take less time vs learning another factions tech.  A way to limit the amount of tech trading.

I assure you I don't want tech trading removed from Elemental. It's an analysis of how a straight-off tradeoff in Elemental would be badly broken, and how to make it work. Turning off tech trading for the game should be the very last design choice.

Actually I came up with the same thought you had, increasing the R&D project level for each tech trading as a fix. My favourite idea is this one:

"Another way is that you can supply another nation with the "fruits" of your knowledge without giving them the secret, i.e, ship them bronze tools and as long as you are giving them bronze tools, they can have the benefits from the tech, but you can withdraw the treaty. In a few turns they lose the tech benefits.

This could be interesting, actually, if giving them bronze tools means they get the tech benefit, and if they continue to have access to your tech treaty for a long enough time, the civilization will eventually uncover the secret of how to make the tools themselves.

This both slows down how quickly you can "give" someone a tech, puts an ongoing cost to being allowed to access it, AND prevents a disasterous strategy of "Okay, you've had my farming tech for four thousand turns, I suddenly take it away and your cities starve to death," issue. I like this approach enough to consider using it in a mod, and it makes a for a really cool series of diplomatic interactions. : )"

In addition to the problem you identify, 2big2fail, which is that 

1) if trading tech has a huge advantage, everyone will trade, because if they don't trade, their neighbors will and they will fall behind, causing tech to be homogenous

There's also

2) The island problem: players starting in locations with fewer neighbors will have greatly reduced ability to acquire tech, resulting in regions of areas falling behind the larger regions

3) The gameplay problem: elemental is a strategy game, but do we want the dominating factor of that strategy to be how well you trade and control tech?

Which are things to keep in mind when talking about how to handle trading tech. I've had a few ideas, what do you guys think of them?