The only difference is that the H4-3D was rebalanced to handle the H4. If you are getting one, might as well go for the H4-3D. Although, the H3-3D will work just as fineI'm about to close a deal on an H3-3D zenmuse.
Is it worth it over the H4? what are the main differences?
I dont have a gopro for it yet but i'm thinking on the Hero4 black.