I was going to get a GoPro 3D kit for the sync cable but then I asked a friend to try if it synced exposure and white balance, which I guess is genlocking? As it did not, disappointingly, I will just run without a sync cable (and housing).
The Fusion 3D could have been nice, but as you say the IPD seem to be lacking, and the FoV is "only" 135° :P In this video
they mention the possibility to have separate settings for each camera, which seems pointless if you want to use it for 3D. I know I never use my W3 for 2D... >_> for that I can use any of my other cameras.