just remember that an accident in a helicopter, which goes wrong to the point of a substantial impact, will most likely give you blunt trauma injuries no matter what you're wearing. The human body can cope with quite high g loading really but only to a point, helmet or no helmet.
Your internal organs will come loose inside you, or if you're lucky, a quick death will ensue with a torn aorta. Not fun reading but a couple of the crashes i'm familiar with, no matter what safety gear they had been wearing would have given them any protection. It's all down to personal choice and weighing up your own sense of risk.