I am a recent convert to NVG's and IR lens SX-16 use. Without any reservation at all.....I cannot state how enjoyable it is to have these new tools for use at night. The only way I can describe the difference is to report the delight I had in making repeated approaches to a completely unlit confined area....in the middle of a very dark part of the forest....on an overcast night....with minimum natural light. Without the goggles on....I could not see the trees....or the ground...from a three foot hover. This was done without any use of man made light. With the goggles.....it might as well have been daylight with the one exception of the diminished field of view.
They are clumsy....take some getting used to....require a lot of head turning....but what an improvement. I actually look forward to flying in dark places now whereas it used to be a stressful time. Night flying over unlit mountainous areas used to fill me with glee...but now it would be a cake walk.
I fly a BK....and due to its small cockpit and the resulting restrictions to the field of view....I do find it a bit hard to see all the way around the aircraft and thus in a busy area of the sky....traffic avoidance might become an issue. However, usually, that situation would occur in a well lit place and thus the googles could be flipped up out of the way.
The other situation that I can see that would argue against goggles would be flying over very large bodies of very calm, smooth, glassy water. The reflection of the stars which becomes very easy to see with goggles could present a spatial disorientation problem exactly like it does with the naked eye.
The IR lens works great in conjunction with the nightsun as well...with the advantage that no white light is displayed. Cockpit lights can be seen inside other aircraft with the goggles at some considerable distance....thus very dim lights anywhere can be seen with ease.
The state of the art equipment is great.....I would shudder to think of having to fly the full face goggles such as the military did for so many years.