RAW would be a big advantage as I understand it. Battery life is a drawback on the DC500. I can get 1.25 dives out of it if I am constantly shooting. Depth rating is 200'.
If given a choice, I prefer to have a seperate land camera. Different lenses and no fear of flooding will allow me to dump more into that camera. When I get serious, I'll likely go to video, so I'm not willing to invest a huge amount into my camera at this point.
Miss, a few minutes of battery life is not right. Even using flash for every shot, you should get more out of it. I did buy an extra battery that I can swap during SI, but I'm still able to shoot video or snap away for an entire dive.