We have been experimenting with both cams, the Hero3 has better quality and imaging (the picture will not be as blown out in the sun), has a better focal range for catamaran use, has sound (although its not great), and the buttons are easier to use. Plus they are only $139 which is not bad for a submersible mini video cam.
This video is all Hero3:
http://link.brightcove.com/services/player/bcpid823619038?bclid=24526455&bctid=663334121It comes with a USB cable and you just drag and drop the video files onto your computer like a digital cam.
I recommend fixing it to your boat on the boom, mast, or other location though as opposed to holding it (unless you've got time to hold it steady).
If you would like one you can get it here:
http://www.rockledgeengineering.com/store.htmlThanks,
Brian
