Once the power to weight exceeds a point where the car struggles to put this power to the ground, that is where 4wd will have an advantage (but only in exiting corners). It may not "handle" any better or worse, but it will be able to accelerate out of the corner sooner. However, once it has done that, the 2wd car may still perform better once out of the corner, due to less transmission losses, so although the entry speed is similar, and the exit speed maybe slightly higher in the 4x4, the speed by the end of the straight will probably be no different to two similar powered cars due to the transmission losses.

This is why the Skyline did so well in racing (it has the best of both worlds), it had the similar entry speed as the RS500s, similar corner speed, but could exit MUCH faster and then maintain that gap because it reverted back to 2wd until it was needed again, so no greater transmission losses than the RS500s on the straights. In the wet, the Skyline was UNBEATABLE.