I think that the only entity that exists within Montage is a performance. If you can switch between single part performances with no sound loss then you can also switch between multi-part performances without sound loss as well. And switch between performances within a live set as well. I think I realize that the performance-only format makes everything, from what we have come to know as complex, so simple that we can't possibly understand it.

"If so what kind of a Performance do you get with one part?" Is this a trick question? You get a single-part performance, voila!:)

"If I want to create a five part performance how do I import parts from another performance?" Some type of single performance importing within the custom performance creation application I assume.

My comment about a single part Performance was that it seems that such a Performance would not be much of a Performance but merely a voice in the old Motif jargon.

That's exactly correct that it's similar to what was once called a voice but now as a single part performance it can have an identity that's much more broad than being stuck in voice mode all of the time. The versatility of these performances are much improved.