i bought a hero 3 (not 3+) as a christmas present to myself. Saved about a 100 bucks.
Also bought the suction mount to mount it to my tank. Still trying to figure everything out. One caution for those considering these devices. You may need to upgrade to a newer computer to be able to view and edit your video's. In order to play back hd video's, you need a fast processor and lots of ram, which i unfortunately am short of with my 6 year old laptop. Bought a hdmi cable to view directly on my flatscreen, but still would have liked to be able to edit, add music etc.
I plan on doing a two day track event in the spring and hope to get some good video.
Bill