This is a negative. Longer keels are harder to knock off course than shorter keels. Longer keels are harder to put back on course than shorter keels. Longer keels have more wetted surface than shorter keels, which hurts light air performance. Deeper keels go to windward better than shallow keels.
Deeper keels get the ballast lower in the boat, which helps sail carrying ability.
Deeper 21 keels find the bottom sooner than shallow keels. The wings supposedly help hydrodynamics. I don't think it's all that great. Wing keels are good at catching kelp, or anything else floating in the water. They also stick in the mud better, if that's what you want.