I don't think that I would say that the agility is improved. Transferring weight is one thing, but throwing weight is another. How quickly a chassis transfers weight is a factor of chassis stiffness. The quantity of weight transferred is a factor of the vehicle weight, the spring rate, the ME of the anti-roll/torsion/sway bars, and the roll couple length.

I wouldn't think that a longer roll couple would ever be a good thing.