This would allow soft synths to dynamically pick their midi generator(s).

As an example use case, iBassist may drive synths on channels 3 and 4 each with different settings ; such an action would also allow flipping the designated synths on the fly, switching the iBassist source for each synth to a diffrent channel), as well as adding other synths to be driven from the same generator through a widget or MIDI binding.