I really do love your mod it gives meaning to end game research however, the reasearch imporvements do need to be drasically lowered or cost drastically increased as i currently have 14 colonists with like 500 - 900% workspeed moving at 26 cells per second which is as you could expect very cool but very OP and laggy :D

Yeah, I agree, for things like global work speed or movement speed the effects shouldn't be so big. I think it would also be good if the research was stacking additively, not multiplicatively, but I don't know how feasible it is. "Special" researches like psychology are good, but work speed or movement speed should be at most around 5% per level, 20% total.

1. The best part about this mod is that it gives us something to do in the end game research. However, I think the biggest flaw of this mod's is that it removed the purpose of other object in the game. There are no reason to get bionic arms, when it's better to spend the effort on research since you get it only everyone in the colony compare to 1 bionic arms.
Thus, I feel like this mod should removed the buff that can be achieved by vanilla way or popular mods. For example, probably remove the movement speed mod since giddy up is so popular. My pawns was running faster than my horses.
There shouldn't be any global work speed buff, so we will have to pick which field we went to do first, and it gives more room for mods that adds body modification. And more reason to go out to interactive with worlds to get better tools(mods) or better arms and legs (vanilla), or better carrying capacity with bags(mods.)

2. Imo, the working speed buff makes sense for some of the things, like construction, med success chance, mining, farming etc. However, it should never defeat the need to getting other materialize help such as prosthetics arms or better weapons.
Therefore, I feel like the buff should be smaller, while the mod should focus on things which we can't get else where from game. For example, higher chances of getting higher quality furniture during construction/art. Higher research frenzy chances, go frenzy chances. This is one way of doing things.
Another way is adding in random resource harvest elements, like we will randomly get more stuff from ores, or plants.

3. Last method I can think of is setting some trade off. For example, we will assume that as we improve in productivity, people also get more stressful. Kind of like how our society currently is. Therefore, you can still keep all these settings and numbers you have right now. However, add that each research will come with mood debuff that last forever. Maybe things before productivity II can stay the same. And after that, if we want to get faster, working better, carry more stuff, we will also have to be dealing with a permanent mood debuff, and the more we research into this mod the more stress we will have to deal with.

If you don't want to use mood, maybe pain shock threshold, psychic sensitivity, or bad immune systme makes sense as well. As we improve in modern world, while we construct, farm do med better, our body is actually a lot weaker than tribal time, isn't it?

4. This mod is plain out OP now, with some other research improvement mods, such as more linkables, or brain in the jar. I can just turtle in my base with 2 researcher and become stronger than fully bionic pawns with only doing farming, research and defense.