recommend me a helmet cam

[Rohloff_Brompton_Rider]

hi all,

i currently have a gopro hero, which is brilliant in daytime but awful at night. a link to low light recording would be a bonus. was thinking new nano 5g

i need a helmet cam that meets the following:-

excellent in low light (most of my riding seems to be in the dark these days)
take 8gb sd card
battery life over 1.5hrs
uses standard batteries (rechargeable)
be 100% waterproof
cost £200 ish

cheers