The HD GoPro is just as good as the regular GPro - except it is HD.
Fogging in a waterproof case is expected unless you take certain basic precautions. If your friend's camera fogged while skiing, either the camera was wet, your hands were wet, or you got snow in the case at some point. Or perhaps the camera got cold and then when the case was opened some condensation formed on the camera -- changing SD card maybe?
In any case, fogging is always user error unless there is damage to the case.
The camera should not be too cool before it is placed into the waterproof case.
It is best to put the camera in the case in a low-humidity environment, like an air conditioned or heated room where ambient humidty is low.
The camera and case must be dry before you put the camera in the case. Your hands must be dry.
Small dessicant packs, available at camera stores, are useful for absorbing any residual mositure. Or stuff some toilet tissue around the camera.
I regularly use the GoPro underwater at shallow depths, and in high-humidity environments. Never had any problems with fogging. RainX on the lens helps prevent water droplets from adhering to the lens in watery environments.