Have a hero 2 and and a hero 3 black. The hero 2 seems a bit more robust, and it's battery time is longer. The new upgrade for the hero 3 has made the MP4 files incompatible with movie maker. You can get wifi for the hero2 by buying the add on, though I have not seen a use for it while flying. I set my cameras one right one left and one front and forget them. Have the 3d casing for the hero 2. Other than a neat gimmick not sure it adds much. The hero 3 uses the micro SD and so you need the adapter or connect camera to computer via USB. There is more to lose with the hero 3 though the black has higher definition capabilities it eats up memory real fast. Bottom line for me is the Hero 3 is certainly a more capable device, but for what I do the hero 2 does the job quite well.
Doug