Giovanni, the thought of having an EVS system on the helicopter is nice. But it would have to move/follow with the pilots head. That would either mean another IR ball, or a mad observer. And the added weight and space needed for it is not available in what I fly.
Just to put this in, most major police departments in the U.S. are going to NVG's as money is available. My department is within the next several months, and in the environment that I fly in at night, it is not soon enough.
I do not know of any departments here that have IMC capability in their patrol helicopters. The best solution is to set up a procedure to reduce that risk. Maybe having someone on board that is not using the NVG's. Or going off NVG and looking, then proceeding to a next established point. Just thoughts.