Justin: Just to strap on when I go on a dive and leave it running, could be shallow on a reef or deep in a wreck. Same as people who wear it on a bike: record everything just in case and if anything important/awesome happens during a dive review it and show it to others, otherwise just record over. I'm not into spending hours editing footage, I like to dive.
6f: Thanks for the link. The depth rating makes it interesting if true, but it's kinda chunky with the LCD and I'll have to look it up to see actual tech specs and performance. Its big brother, the HD30W sure looks a lot like the AEE Magicam S70, which I also considered and meant to add to the list. From what I can see it's Chinese or Malaysian-built, but the quality of the S70 rivals the GoPro. A tad more distortion on the edges and audio quality not as good (not a problem for me), and the colours are warmer, which makes it harder to adjust it in post-editing (also not a problem, probably an advantage for U/W) - but rated to a lot deeper than the GoPro - just in case I decide to do a Dave Shaw
At the moment it looks like I'd either get the HD2 and have a cheap and cheerful camera for 100 quid or if I want to splash out and get something higher-end close to the GoPro and deeper-rated for half the money, go for the HD30W/S70. A looming trip to Egypt is pushing me towards the 100m-rated one...