I've been using V-Stack on my PC to run all of my soft synths/samplers. It's worked fine for me and my only gripe is that I can't do MIDI sync with it. Also it doesn't seem like it will be updated by Yamaha/Steinberg.
Have a lot of people switched over to Kore? Does it work well. I used to like NI a lot and own the Komplete 2 bundle. But I had a bad experience with them and Guitar Rig 2/Kontrol Rig 2. Basically, I have been beta testing a product for 7 months. It works, but there have been a lot of bugs and they have been slow to fix them. Is it the same story with Kore?