Since the DGX 650 won't be used for gigging, arranger capabilities were not a high priority for me. Besides, a person can midi from the DGX to another arranger, should that be desirable. That's what a piano playing friend does.
The DGX 650 still has no conventional MIDI ports. With the DGX 630 we have in church I haven't found any possibility yet to connect it to my Integra or any other instrument. You cannot just connect USB to USB, it won't work. I still have to try it with my iConnectMidi interface, which is said to have the Yamaha protocol loaded, but again it cannot be connected with normal USB cables as you need a USB cable with two identical ends (USB-B to USB-B).