When recording my motorcycle rides, my biggest issue with the GP10 unit is that when using the external (in unit) mic, the wind noise overwhelms the voice from the headset as well as any engine noise. When I turn that off, I can't capture any engine noise, which is essential on a motorcycle video.
My suggestion is to either statically fine-tune the sound mixing on the GP10 firmware, or allow the user to select the desired setting.
Another option would be to allow the external and internal mics to be recorded in separated tracks, ideally stored in the GoPro-generated movie-files. But in case that is not possible, storing the headset audio on a separate file at the unit itself would also be acceptable.