So now I have been looking around many times on cameras. I have a setup with gimbal that require the gopro camera. But for any other and maybe future setups, I might be able to have a sony placed instead.
You would never have to run it through a stabilizer program which takes forever. And it doesn't lose quality by stabilizing by the source (it seems). Also the image quality and sound really does seem better on the HDR 15.
Image stabilization wont do much for you on a quad, here is a fair comparison between the 2 on a multicopter.
Side by side in smaller windows the sony looks ok but highlights are way overblown, sharpness looks better in the small windows in the sony but when made full screen you can see its just post image sharpening and looks pretty bad IMHO.
This is also just comparing regular autom mode in the gopro vs sony, where the black really shines is if you use it in protune and cam raw then there is no need to worry about colour balance or other image settings forced in camera. You can set these as you like and end results will blow away anything possibly in camera by either camera even though the in camera settings going by that video I prefer the GoPro still at full screen.
I dont use auto mode in the gopro cameras anyway because I dont like the way the camera does things on its own. I dont think the sony is even close to the hero3 black sorry to say.