I have had a NM200 for a little over 2 years. I have run some nice jobs that have made me a good profit. Like any tool, you have to understand it and take care of it. I have one of the first machines produced and it still runs pretty good.
Expect to adjust it and tighten gibs every so often. The back lash is still under .002" but I have cut a lot of metal and they had P5 ball screw at that time. I have the older AC 4500 RPM motor with the SunFar driver and had no serious problem with them so far. I see that they have gone back to the AC motor and driver. Though I wish I had the 6K spindle speed, but I get along just fine.
I have read some posts and have responded to some negative posts in the past but was attacked by other members. I have stopped responding to some of the posts, but I will say I had no problems working with Novakon. I will throw my 2 bits in here and say maybe some negative stuff may be coming from their competition?
I find them very easy to work with. Good luck on your selection.