Samchap,
I've not used rifle scopes, but I have hunted with night scope binoculars.
Some thoughts:
Gen I,II andIII are each a great improvement over each other. I woould only recommend the Gereration III. Like most things you get what you pay for.
Infrared illumination, is a great help. It is an expensive option on some units. But the IR illumination works totally independent of the nightvision unit. It is much like a flashlight, it add brightness to the picture. So as a cost item a cheap IR unit can be hand held or taped to the rifle barrel. Night vision scope still require some illumination. On a moonless and starless night you will not be able to see much, ambient light is a great help. No moon and clouds will mean useless, even Gen II, unless you have an IR unit.
I'm not sure what your needs are, but assume they are legal? IMHO the rechargable 1 Million CP spotlights and a good 3x Leupold scope works better than the nightvision stuff.
I have looked at the Soviet surplus stuff (most is GenI), and it appears to be a bargain for the $$$. But at the same time, they are not what most people would like...a bright sharp image. The military use is to see WITHOUT being seen, for animals the bright spotlight doesn't draw fire toward you like a battlefield situation would. In fact the spotlight, as jacklighter have found, actually stablizes wildlife.
BEAR