@sage 2.7K medium FOV gives a very sharp picture. With alignment adjustments one loses resolution, so rendering the final video to 1080 gives very sharp results, compared with shooting in 1080. 60p has the advantage of smooth motion and allows a closer time synch across the two cameras.

@zcream The GoPro 3+ also has synch. For the 4's, the Smart wifi remote starts and stops each camera simultaneously. I use a clap and/or a clicker for each shot so that I can align the two views in the editor using audio peaks. This works fairly well, and the higher the frame rate the less room for error (hence the 60 fps). Many people shoot 3D with two un-synched cameras and use the audio synch method.

The GoPro duo case for the 3+ fits the 4's the same, so that provides the physical alignment. GoPro has indicated that it is working on getting synch for the 4, like the 3+.