I have decided to buy a keyboard with 61 keys. I actually decided to buy a Komplete Kontrol A61, but I have found that it doesn't meet my needs as I need a sustain pedal input for my piano playing. And then there aren't that many NI keyboards to choose from, so it has to be a Kontrol S61. But I now see that there is both an S61 MK2 and an S61 MK3. What is the big difference between them and is the MK3 worth sacrificing that much more for?