Tried out the new Sony HDR-AS15 this morning.
Despite the camera being very small and light I do not think at the moment it is suitable as a helmet camera.
Any chance of rain and you need to use the waterproof case, currently the non-waterproof mount is not available.
The waterproof case is very sturdy and well made, as is the headband mount but they are a little heavy so when the camera, case plus headband mount are combined the extra weight is noticeable, after 90 minutes riding this morning it became unpleasant.
Also Sony have seemed not to have learned from
GoPro's problem with a fully enclosed waterproof case and it suffered from fogging, I do not know when it occurred, only noticed when I took the helmet off at work.
So far the comparison with my Contour+ is not favourable, the C+ is basically waterproof enough not to need it's waterproof case, so significantly lighter and no fogging problems, plus it can be mounted flat on top of the helmet, my preferred location.
As for video quality that is something for later.