To answer your question. the GoPro 3 will work with the solo and the gimbal. but the onscreen controls to start / stop video or change to photo mode will not work. I get around this by setting the GoPro to auto start video mode on power up, and editing the video on computer.
the BUS connector on the GoPro will charge the device, so at least you don't need to worry about the GoPro running out of batteries.
the only annoying thing is that when you've landed, and powered off the drone - the camera will still record. I can't tell you how many of my videos end with a shot of my toes, or a walk back to the garage.