I was researching dive operators, and happened upon this post. Thought I would put in my two cents worth.
My rig is a Nikon D300, Subal housing, twin Ikelite strobes and a Hartenberger focus light. I also frequently carry a Casio point and shoot which I can get into places my big (and expensive) rig cannot go. DSLR's are fantastic, but you can do great things with P&S cameras.
Where a lot of folks "muck-up" is in their software. We did a demo at our Pacific Northwest Underwater Photography group meeting last year and did two tasks in a number of different programs: i-Photo, Elements, Photoshop, LightRoom, Picassa, Aperture, and I think two others. White balance and backscatter removal were the two tasks.
Almost everyone who used i-Photo, Aperture, Picassa, and Elements went out to purchase LightRoom. After seeing what Photo Mechanic can do as a browser, the higher end shooters purchased it and subsequently bagged Adobe Bridge. There is still a need for Photoshop/Elements with LightRoom, but it is getting rarer and rarer.
Bottom line from our group: whether P&S or DSLR, shoot RAW, not JPG. LightRoom is the software of choice, be it PC or Mac, and Photo Mechanic is the way to go for a browser. Stay away from manufacturer's software.
Hope this helps some folks!