Civ IV uses this fantastic option to balance Technology Trading.
Why not implement this in GC2 as well ?

Currently you can either a) trade all techs you can get your hands on or turn off Tech Trading.
Both are sub-optimal choices IMO.

Being able to trade ( or trade for) every possible Tech does not work well within the idea of creating "different" races as all races start to look more similar as the game goes on.

Disallowing Tech Trading on the other hand takes away a very interesting and strategic part of the game.

Civ4 has an option which is called " No Tech Brokering" and which gives you the best of both worlds IMO.
With this option "on" you are only allowed to trade Technologies which you have researched yourself.

Meaning : In GalCiv2TA
1) you can still trade for General Techs and/or Race Specific Techs, but you cannot "sell" them to anybody else.

2) this way, races can trade their Race Specific Techs to somebody else without fear that that other race will sell this "knowledge" to a third party. As such you really have a monopoly on your race specific Techs and you sell them when you want, to whom you want without anybody making a cut block on you.

3) with this option in play, it becomes even more important to keep a close eye on what your opponents are researching so you can figure out which race can possibly help you with developing your research and which not, which race to befriend and which to ignore.

Personally, I think this option would improve the game in a big way.