typically, a mosaic is shot with about a 20% overlap to take care of the edge issues...
If you are taking images from the same altitude, the Nex will look quite a bit different that the Hero.
There is the video capability of the Nex as well, but you will need quite a bit of memory.
This adventure is going to take a lot of memory capacity, you need to figure in some of those terrabite backups, many have an SD card reader built in...