Digital Night Vision

Can anyone school me up a bit on digital night vision? I have been doing a little research and understand the basics. The claim about which I am curious is how the quality compares with standard tubes. Some of what I have seen claims that a decent digital unit is similar quality to a gen 2 or gen 3 tube. Does anyone have any experience, or can you point me in a good direction?

http://www.ar15.com/forums/t_6_18/317705_.html

I have a PVS14 Omni VII Autogated manual gain, while i have nothing to compare it to, its pretty awesome. Add a surefire vampire light and you are a real operator.