It does tend to depend upon what generation of gogs you are using.
I started out on Gen 1 which had a terrible tendency to ‘iris’ out which was a system to protect the eyes by closing the goggles if a light source was shone directly at them. Bit of a bummer as they could take between 30-60 seconds to open up again!!! You can imagine the implications!!! The later generations fixed these problems and increased the field of view dramatically.
Weight is an issue but unless you have tried them with a properly fitted helmet you aren’t getting the full picture. The goggles are attached via a clip above the visor and then the battery pack balances the goggles by being attached to the back of the helmet. When not in use both can be removed. The combined weight though can put a strain on your neck.
Current mixed mode (NVG/FLIR) displays are pretty spectacular with some even using retinal imaging to overlay onto your visual picture. Not sure if they’ve hit the civvie market yet though! ;)