Using gopro hero 3 white/black with 3d- anything to watch out for?
Ensure that you purchase the 3D kit for the current generation of GoPro Black Edition.  There was a 3D kit for the older GoPro HD (and they have a terrible set of similar names for all their products).  I take it you are thinking of the Hero3 Black, Hero3 Silver or Hero3 White and not the Hero3+ Black or Silver?  These are different products and it looks like the (more recent) Dual Hero System is designed for the Hero3+ products and not the Hero3 ones.  You should be careful not to purchase the older 3D Hero System, which works with the HD HERO2 &amp; the Original HD HERO, but not the newer cameras.  

I have only read reviews on using the older 3D system.  They mostly concluded that the 3D software was good and produced reasonable results in a reliable way.  It was observed that the cameras seem to start with a small offset (1 frame I think) and the reviewer summarised that the software might be designed to deal with this difference.  If you choose not to use the bundled software, you might want to check the timing of the two video sources carefully as you might need to take steps to synch them.