As an experienced user of GoPro cameras in underwater, natural light (see my youtube channel: Richard Fast), be advised the auto color balance is really bad once the red disappears below 20 feet, or so. You will get nothing but green. This is not the case for the BR recommended Sony video board sold here. I found it maintains good color balance all the way to 100 feet. The red is gone, but the remaining colors are correct. If you are going to use a GoPro plan on investing in some really good color correction software, and spending a lot of time in the editing room. If I were going to spend the money on a BROV2, I would invest in small in-line DVR’s and record video from separate board cameras. This is especially the case in low visibility water, as you say you will have.
Also, no two GoPro cameras interpret color the same. When you try and meld together the different camera outputs it will drive you crazy.
Just something to think about.