Just me but, look, if you want a (small) camera for underwater from Canon then there are two current choices, the G11 and the S90 (and the recently discontinued G10 and A590/A570).
If you want an SLR for surface shooting but cannot afford a 2,500 dollars housing or the size and weight restrictions eliminate it from your consideration (for travel) then there is the Canon Rebel T1s.
Consider the Canon T1S is around 750 to 800 dollars. The Canon S90 is 400 to 450. Purchase both for about 1,200 dollars. Get an extra zoom tele or whatever for your SLR and get a housing for your S90/G11 and you will have all bases covered for the price of a mid range dSLR without anything but the camera and kit lens--or very close. You will have a dSLR for surface and travel use and a Pro-sumer level P&S for underwater and pocket.
You have to quit thinking in terms of a one camera solution. The OPs question, me, I would not want that camera at all for anything. It is too big for the pocket and it is not a interchangeable lens SLR so it does nothing well.
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