I think the benefits are static for Scientist hits. Each hit is worth a percentage of a Research Center activity for the turn.
I may be wrong, but the inference is that each Technology requires a certain number of reasearch points to achieve. The more advanced a Technology the more points are required. Each Research Center generates a certain number of points per turn towards an assigned Technology. I don't know what the equation is, but for the sake of discussion, let us say that it is
10*SQRT(RCs_Assigned). Thus one RC assigned to a Technology will net you 10 Research Points per turn, while 2 RCs assigned to the same technology would net you 14 Research Points per turn, and so forth.
My hope is that a Scientist hit garners you 10 points per hit (given the above formula). It's worth a solo RC worth of research. My additional assumption is that the greater the rank of your Scientist, the greater the chance of multiple hits in a turn.
FWIW,
-SK