Cletus, I just did a little looking for you.
I don't own a go pro, so I have no specific experience digiscoping with one.
But, looking at the Hero 4 black camera, it has a mode called Protune.
The Protune setting allows you to control white balance, ISO, and shutter speed. Along with exposure compensation and color and sharpness settings.
The one thing I don't see is aperture control.
Maybe go pro cameras have a fixed aperture, maybe they must always be controlled by the camera processor.
Anyways, with this setting, I see no reason why the go pro can not achieve quality similar to most low end, point and shoot cameras.
However, it is a fairly limited camera. Iso adjustments of 100 200 400 & 800. Thats it.
I could not find its shutter speed range listed anywhere, but if it is as limited as the ISO range, you will suffer in certain situations.
If I were you, I would go with another option. That is if quality is your main concern.
The go pro is capable of incredible quality, but I doubt its processor is programmed to understand and deal with digiscoping.
So, you will probably be better off using it in the protune setting, and that seems to be quite limited.
Thats just my opinion, based on nothing more than specs listed on go pro's site, and personal understanding of digiscoping concepts.