A quick look on the GoPro site, I see that they have upgraded the Hero3 substantially over the Hero2 and HD versions. We're not talking just more megapixels, but new lens, sound capabilities, faster, smaller, lighter, blah blah blah. The compact video camera market is very popular, and changing/upgrading rapidly. When I upgraded from my original GoPro, to the next version(HD), the quality jump was huge. I believe the jump from my HD version, to the Hero 3 Black, is another large leap forward. My guess is, the jump from a Hero2, to the latest Hero3 is not as big, but you do get some performance and quality for the extra $.
Plenty of YouTube videos on this subject. Make sure you watch the videos in HD
http://www.youtube.com/results?search_q ... 1rEsRcZHo0Things to consider. Low, and varied light performance. It's a big factor in fishing situations. Outdoor sound quality. Another big factor, since wind can muffle, or completely take out any other sound. Underwater quality and issue for you? If so, the Hero3 Black will give you the best quality. Ease of use. The controls on my original and HD versions are less than ideal. The button, and menu function sucks.
Personally, I would not buy anything older than the Hero2. If I were to upgrade from my Hero HD, I'd go with the Hero3 Silver, or Black.......and since the market changes so often, I might wait until they upgrade again an buy at discontinued prices.
briansII