From the other side of the pond I will tell you that we do things very similarly, the wonders of an exchange program perhaps. Another reasoning to consider is that way off shore over the water at night with no moon or heavy overcast should be considered IMC, and hence no place for a VMC helicopter. NVG's obviously have limitations, and I have plenty of experience where they have presented no horizon...mainly because there was so little light for them to amplify. The US Navy and Coast Guard require such overwater night operations to have two instrument rated pilots.
As previously posted, flipping goggles up and down is sometimes a requirement to accomplish the missions, but it should be pointed out that the practice has also been cited as a causal factor in two nasty crashes that I know of. One in particular where the crew went to unaided on approach to a ship and shortly there after (5 min) entered an unusual attitude and splashed inverted right next to the vessel, nothing wrong with helo.
For Hoisting, I personally don't flip mine up, but vertically raise them to a level or tilt them up to give me more vis under or around them for hoisting and occasionally catch a glimpse of the horizon. This also eliminates the possibility of drawing a crappy goggle mount that will drop them back down in your face at the most untimely of moments...good times there. The safety pilot however, will keep them down and will be watching the instruments as well. For an emergency flyout, I suspect that will be a dual piloted maneuver for a short bit due to the lag time of the flying pilot to switch gears from visual position keeping to swooping away into the black abyss.
If horizon doesn't exist, well there you are wishing you had a HUD attached to those NVG's with an artificial horizon, but you probably won't find such capability in a VFR helo. Those are cool toys, but even then, I found myself maintaining more of an instrument scan than looking at digital info on the tubes. Old habbits...
But my original motivation here is to say that once you go feet wet far enough off shore to lose any ambient light from land, regardless of the forecast, you can easily find yourself with the need for instruments regardless of what is helping your eyes. My advice is to avoid that environment unless you are dual piloted and you both have polished instrument skills.
