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.
It’s still like that and even better, given that from the 3.5 to the 4 there have been 6 years of development. But let me summarize: you make a lot of noise for basically nothing and in the end your problem is that now you have to pay a moderate amount for the privilege of running such a (in your words) wonderful terminal server. And of course you want it exactly the same on Mac. And presumably for free. OK, we’ve got the point. Now we’ll get back to work. Thanks for your insightful comments.