Francois Bouju is the man running the show these days at Daniel Bouju. He's incredibly nice, knows a lot about distillation, and taught us a great deal about the region and its wines when we visited his Cognac estate. He impressed us beyond any expectation we had going in.
His vines are planted in the best soils – rich limestone which helps to preserve acidity in the fruit – and he is a stickler for detail. The reason the Grand Champagne region makes what is considered the best Cognac is because the soil creates grapes that are fully ripe with high acidity levels and low alcohol. This is important because distillation is about concentrating the flavor of a base substance. If you've got a wine sitting in a tank oxidizing, you're going to have an oxidized flavor in the Cognac. High acidity levels help prevent oxidation while distillation is taking place and prevent the need for stabilizing sulfur (none of us want to taste a distilled fart). At the same time, you need wine with a low alcohol level as to not overpower the flavor of the fruit. Full ripeness is also necessary to have any flavor at all. You can't simply pick early to preserve acidity because your wine will taste terrible. Bouju's high-acidity grapes allow for a pure and clean-flavored Cognac, free of any impurities.