i think quantum is very different. it has 4 GB for samples. Pro X has 50 GB (+150 GB built in). That means you can really sample each key in multiple layers (maybe… no real specs on that, but the piano sounded like that)…
so the real deal is/or would be to add different samples to each key… so in general you should be able to add some short stems (lets say) to the left hand part and play a different layer on the right hand…
still, its all about what happens, when you really play it and how easy it is to create sounds… i have a lot of waldorf gear and its great, but really hard to program… all DSIs i have are pretty much super direct and easy to program and all the parameters really are designed to always give you the sweet spot… thats whats makes the difference to me.
At the end just press a key and hear a sound really will not give you any advantage over a computer… but really playing (!!!) with all the parameters live. a lot of people seem to use samples just “static”… dial in and loop… but playing with all the parameters give me that spice and unexpected sounds… kontakt vs Pro X or Quantum is maybe the same like comparing octatrack with ableton… i prefer a intelligent designed instrument that supports your expression as a musician like octatrack or, well Pro X…so Pro X is nice as soon as you can upload your own foley/modular crazy samples and go wild with all the modulation options 