Very little, in my opinion, assuming that the controller of choice can provide you with the degree of control your module requires. The thing to keep in mind is that the keyboard of a workstation is designed to control its internal module, while a dedicated controller is designed to be generic. So, generally you would have work to do to customize the controller's settings to match the level of integration that a DAW has with its keyboard.
That said, the vast majority of my synths and samplers are modules, and my main controller is a StudioLogic.