I am forced to use Digital Performer for certain kind of jobs because the MAS protocol associate with VEP is really powerful and open a massive amount of possibility and flexibility while working with VEP.
That kind of protocol basically allow the user to have a sort of double midi send so that in a single instance of VEP it is possible to have multiple 16 midi channel kontakt (for example) instances.
For scoring purpose it is really useful and allow composers to have more control and a better organised VEP interface.