3D, the human eye is most sensitive in the green colour band which is the main reason for the colour of the image in NVG. I believe there are some experimental sets that produce a yellow image but I have not used them.
Thomas Coupling - I am sure that some of the improvements between Gen II and Gen III enhance the signal to noise ratio when light levels are high and prevent the automatic gain from closing down the goggles as much in these conditions. I think your 'experts' may have got you cheap goggles but not neccessarily for the right reasons. Gen III are vastly superior to Gen II and the differences are highlighted in difficult conditions. If NVG are too sensitive for your ops then you probably should be using white light or FLIR. In what conditions were they considered too sensitive?