IMHO Rep was not great but better than anything else. As Alan stated, the additional hammer is next to useless since research is all that matters. The map did not have enough food to support many specialists, so I couldn't fully benefit from Rep (as I wanted to run as many cottages as possible, I farmed just enough tiles to support them). But in my game I did get a quite early SoL (~1250AD?) for a free specialist in each city, so I still got a small benefit. Which brings me to another point, in a PA the empire-wide world wonders (SoL, Three Gorges, Space Elevator, Eiffel, etc.) are even better as their benefits are shared. And yes, I did notice a large impact on research in the first few turns of the PA in both games, however IIRC it was more dramatic in the game the PA came late (Robotics from 7 turns to 1 turn?). My guess would be that the AI would have a lot of spare cash so it could run 100% research for a while. Even then it seemed excessive to me. After that I was getting some 170gpt from him to allow me to run near break-even at 100% research, so his contribution to beaker generation was lower. Not sure if it would be better to keep him at a higher research rate, if the AI techs at a discount. Is it the same discount it gets to build stuff (20% at monarch)? Another thought is it could be better to get another ally (say, Roosevelt) and still have Mansa as a non-PA tech-trading partner.