Firm and strong YES for keeping tech trading and brokering in the game! Hell, NO greyish and shallow "may I trade my 15 in Magic for your 15 in Warfare?" like in Elemental. And NO to alliances put too late in the tech tree (= essentially crippled).

And of course, ltes keep an option to turn it off as well. You dont like tech trading and brokering? Turn it off. Problem solved.

With this approach, nearly everything is human-exploitable, I am afraid. Still its a matter of choice: you want more challenging game? Turn tech trading/brokering off. Or do not use it. Or use it only with non-military technologies. The choice is up to every player, but why to deny it entirely?

Diplomacy building/bonuses would be still very useful. You can get peace easier. You can make other civs wage war on each other easier. Etc.

Tech trading is an important factor for game immersion, in my opinion. Yeah, of course, we need to flesh this out in terms of balance, AI decision-making tresholds or otherwise: maybe we can trade blueprints that still need to be further developed?

But do not take the super nerf way of Elemental, which resulted in - compared to Galciv - very poor and substandard diplomacy. In EWOM and FE, the diplomacy might be exploit-proof, but it is no fun, intrigue, its contribution to the game is extremely limited. There is no point in being human like faction, specialized in diplomacy, because it would give you nearly nothing.

Now compare that to very funny and living diplomacy in Galciv II...

Keep the choice and let everybody to decide by himself. Thats my two cents.

Hmmm,.. I think maybe you could fix some of the problems by dividing tech into "discovery", "research" and "application" parts. 

"Discovery", you would get more or less automatically by interaction with another civilization. The more use a technology sees, the harder it is to keep it secret.
"Wait, the Terrans use laser technology to make 3D pictures? 

"Research" is a bit harder, because even if you can buy a gizmo on the open market, the odds are it won't come with a scientific paper attached. Still, you could simply have your diplomats go to the local library, Again, easier with wide-spread older tech, and if you have a good relationship with the civilization in question.
"OK, now I know what the theory behind holograms is." 

"Application" is the hardest part. It's not like you can plug your alien gizmo into the wall. You need to produce the tech with an industry base that's nowhere like what the other civilization uses.
"But how do I get it to work in liquid methane using biocircuitry?" 

Basically, even if you acquire alien tech, you still have to spend research points adapting it to your specific needs, making it not an instant improvement but something you have to work for. If you trade for ten techs, you'll still spend the next forty turns or so deciphering how to produce them; more depending on how different the other civilization is from yours. (Adaptation costs could differ for different techs, making some techs more desirable to trade for.)

Application can also be an ongoing process, making your existing tech better; The new quantum computing autopilot you got may have fancier piloting skills, but the older one takes a lot less space, is cheaper - and can take a hell of a beating, too, before breaking.

This sort of obstacle makes it less profitable to trade tech - but it's still important to do so; you just have to pick and choose what techs to spend resources on. And a more diplomatic species will still get more tech discoveries - only it's done automatically, with a small chance to get one every time you trade with, conquer or otherwise interact with members of another species. 

... I think that techtrading should be changed , how it was, IT WAS TERRIBLE and it is terrible in Fallen Enchentress.

What I would have in mind is :

1,) You only could TRADE Techs, where your empire has qualified to Research them

2.) There should be DIPLOMATS/HEROES in the game, which could be used for different tasks. BUT that Heroes should be able to DO ALL ... spying, politics, trading, science, military ... how many of that heroes you have in your empire DEPENDS how many People you have ... let say every 5 000 000 000 you get one hero ,,, this could be improved with education ,,,

3.) That Heroes could be sent to SCIENCE Tasks ... so you Need an Agreement with another empire that they will give you the blueprints for a new tech ... so the hero has to travel there and he will be teached for some time , after that he comes back and gives his Information to the Research department and the Research time will be REDUCED .. depends how developed the other empire has been and how developed my own empire is and how good the hero is in that field !

So if you Need Research send all your heroes to tech trading ..
if you need Money send them to trade missions ...

So what they are doing depends at the Situation in your empire ! But of course the longer you use one hero for science Tasks he will improve in that field ...

SO TECH TRADING should be only an % improvment for the research department,

like everything else (spying, politics ...) ! 

PS: As I have played somehow all 4x games the last 30 !!! years (starting with Apple II+) I have millions of ideas ,,,
I remember still some Hotseat games "Reach for the stars (SSI)" with friends, who already left our world R.I.P.

So rather than tech trading, why not add the feature of "Ship trade"?

For example, I'm human. I'm not into the military tech, but I have an ally who have good military ships. So rather than I trade their tech, I could buy their ships instead. Vice Versa, if I'm good at military tech and my ships are good and I have a weak Ally that need more military hardware, I can design two ship that almost identical. Say, F-16 for my own military and F-16 Monkey Model for export. Then I put my F-16 Monkey Model design to my trade display boxes so when my ally need more ship, they can buy that license and produce that export version of my F-16 to be added to their military.

So, by buying design license, the empire can produce a starship without researching the techs.

That already exists in GalCiv. Granted, you can't trade the designs, but you can trade the finished product.

As far as the AI is concerned, it doesn't really care where the ships are stationed. If they are at war, though, I believe they do move them.

I have been thinking abit and think tech trading might be sensible if you have a system where you have to send emissaries (a hero/champion type) arround to do diplomacy. Then it wouldn't be something you did every turn with every civilization.

My two bases are economy and research, with military to scare other civs. I like to trade techs for other techs, money and then planets. Technological Conquest of planets ftw!!!