I have one with an NM 800IR. I have to admit, I haven't had access to anything else to compare it with except a really old gen 1. The picture takes a bit of fiddling with , along with running the NM800 on its' lowest settings and adjusting the positioning of it so it doesn't white out the picture. I think the picture is OK, useable out to 300m anyway. The inbuilt illuminator gives a grainier picture, and at distance the benefits of the NM800 are clear.
Based on my experience of this unit, I decided that I wouldn't bother getting a demo of the DFA75 unit I was pondering, and that for now this would just be used for observation before turning on the lamp.
I think there are major improvements to come in digital NV, and the prices should drop as well.
I could be convinced to part with my whole setup which is in a Peli case should you wish...