I would think that the 'smoothness' of your particular bike or drivetrain would be limited by its weakest link. If your chain/pedals/bb/tires/etc weren't perfectly cleaned & lubed/packed/seated & inflated properly/etc, then I would imagine that having cartridge vs. loose ball bearings in your hubs would take a backseat. (Not to mention the riding surface, bike weight, etc...)

For everyday street use, anyways.