I think that tech trading in this game is a little too easy.
When I compare the researching of me and the alien races, I almost always seem to be lacking. On the other side, I still have most of the stuff, the others researched due to trading. I'm not doing anything but from time to time checking what they have and what I have. I put all their non-military techs in the list and all my non-diplomacy techs. I balance it out with money until it is green. Then I move on to the next race and trade them what I just got. I don't even try to be cheesy here, as I really only do this from time to time and not everytime I get something new.
A little focussing on getting diplomacy techs, who are extremely cheap compared to others, is all I have to do.
However, beeing able to keep up in technology with that little researching on my own side, seems to make the game somewhat easy.