As I've been playing DW the past few days, I noticed this problem with trading tech too. It just seems to throw the balance of the game off.
It's far too easy just to always trade tech with your allies, over and over every time one of you researches something.
And I like to play with research at the slowest speed, so being able to instantly gain technology hits me right in the heart .
I had the exact same issue with GalCiv II also, but that game had the option to disable tech trading entirely, when creating a new game, which I happily did.
I would love this option on Distant Worlds as well.
Speaking of changing how the whole system works, I too like the Civ V way better.
And when you think about it, it actually is pretty realistic. Both parties sign a research agreement and pay a certain amount of money, then both parties gain
a small percentage of research boost. It makes sense since both of you are 'putting your heads together' to work on tech.
You eliminate the problem of instant tech, and can have these tech treaties to strengthen your alliance.
The game already has various ways to boost your research speed anyways, and this way would also improve your ally relationships.