I used NX 3.5 with linux machines a few years ago. It was wonderful. Remote sessions were opened only with user credentials and without being presented at local display, I also authenticated with my own ssh key. One local user even did not notice that there were other users with graphical interfaces running in parallel. Accessing remotely did not expose the session to whoever could be next the computer. This is an important issue.
Since Linux as desktop have many problems and too much misanderstanding between distributions I migrated to another unix like SO, the OSX. Where I finally integrated my PIN apps with my cel phone and tablet.
Although it is unix , the same behavior does not occur.
It would be nice if it could happen the same way as with Linux. A sharing display app to give remote support is VNC or Teamviewer or RDP. NX should be more than that. An app to really work remotely, not depending on third party internet server authentication, specially now with NSA exposed spying. Who knows if third party authentication servers places back doors to governments or others?
VNC also does not have the graphical quality and security robustness as NX/SSH.
I hope you could improve NX on OSX as it was for Linux.