i have a schroth hans. £400 worth of head and neck support, if you can afford it buy one!
remember a proper helmet to suit is required, you should not retro fit the hans clips to a helmet.
i bought one after a head on into a fairly soft barrier/tyre wall at cadwell a few years back...
i have crashed since buying/wearing one and it was again a head on. walked away feeling a slight twinge but nothing to worry about at all.
the first accident hurt me for at least a year!
crash without hans 40mph impact
crash with hans roughly same speed impact... (crash at the end of the video)
they feel very restrictive the first time you wear one but once lapping you forget its on.
buy one if you can.