As we appear to be onto hypothetical helicopters now; for ultimate passenger safety, if a helicopter such as an S-64 Skycrane was used, and passengers travelled in a purpose-made detachable freefall lifeboat suspended underneath, then the hazards of passenger evacuation, risk of drowning/hypothermia, need for immersion suits/liferafts etc. would all be avoided.
Possibly not the most comfortable way to travel, but probably safer than trying to float a helicopter in the North Sea with the weight of engines, gearboxes and rotors above one's head.