Hello:
The only difference that I am aware of is that the NSI multiplex signal repeats after 128 channels and the Sunn will only program to 64. It is all a matter of setting the DIP switches for channel assignment. It works as a binary encoder. All off is ch 1-4, on off off off is ch 5-8, off on off off is ch 9-12 and on on off off is ch 13-16 and so on. Be sure to start from switch 1, sometimes it's hard to see on PS300 & PS600 models. They put those dips internal. On my units, I put standup dips in and provided access through the sheet metal so I could program them at the show without disassembly or even removing them from the trees.
Don T.