As far as I can see, the GoPros are great for what they were designed--action videos.
I maintain that if you are recording audio and video, and want to do it in all at once, you need line inputs to get the best sound. I don't see where they have these inputs.
Our keyboards output studio-quality sound and it's a shame not to capture that when doing videos. Also, you won't have to worry about picking up peripheral sounds and noise. You will only record what is sent from your keyboard and what is picked up by your vocal mic.