If you are looking for ready to go units there are none and I doubt there will be any fully functional Gopro controllable ones until 3DR develops options for it.
To make it work with the GoPro as the Solo gimbal does 3DR needs to develop the interface and push it out in the form of firmware.
I would not except anything like that this year. Be surprised anyway.
Some guys are hacking other gimbals onto the Solo but they really don't have full smart shot capability (no gimbal tilt) and they cant control the GoPro.