why make it so complicated, i would made it like in galciv2 (i think). there you would ge bonus points in research, if you would have an research pact. something like this should be easy to come by in dw too. if you make an research pact / contract, you would get some research points for the selected research category, like an additional lab. let's say it would be a percentage of the research capacity of the other empire. in this case i would also limit the amount of research contracts an empire would sign, maybe to two or three.
One good reason is that the tech leader, if sufficiently advanced, will not gain anything from research treaties. You will need to find an empire with tech you want but don't know and who wants some of your tech which they don't know. Of course the computer would be set up (generally) to not want to get the raw end of any research deal... It is not just a general 'more research' mechanism but one of diplomatic bargaining, and possibly, counter-offer. These techs for those techs? No, no, we want that one. Well, how about...?
Secondly it is good to have some cases where you will lose out from making a research pact and to require you to maintain decent relations with your research partners (and not just to attain decent relations momentarily to make the treaty). The money requirement is to make sure that these cannot just be spammed with everyone right from the beginning of the game. Putting a hard cap on the number of research treaties will work against the diplomatic powerhouses who you would expect to be able to make more treaties than xenophobic isolationist races.