Short answer is yes. In a lighty loaded ball bearing, the viscous drag of the grease will significantly exceed the friction of the rolling elements.

But it barely matters anyway. When comparing rolling drag it's important to consider the torque rather than just the drag. Because the bearings are so close to the neutral axis, hub drag would have to be staggering to matter. Small differences between various hubs are comparable to worrying about the pennies in a jar when the mortgage payment comes due.