well, IF the book is right and you tune every other aspect of the car to perfectly suit the change in weight bias (like increasing front spring rate accordingly to the added weight) and the car was 50/50 balanced in the situation you are looking at, going away from the ideal 50/50 would result in worse cornering performance/lateral g-force.

My question was: If that is true, why do i get more steering when adding weight to the front? it could've several different reasons like less than 50% vertical load on the front tires due to weight transfer, or more tire contact patch because the shocks (which weren't perfectly set up for the previous weight) suit the new weight bias better and thus work more effectively.