Canon S400 or S45?

Looking into getting a low budget underwater digital setup. Basically want something good for snapping pics on land and occasionally on dives. I've done searches but am having trouble deciding between the Canon S45 or S400, each with their Canon underwater housings. Both are around the same price and have similar features. The S45 looks like it will give me more control, but most likely more than I will use. S400 is nice and small, and looks like the buttons are easier to use underwater. Will I see a big difference in my underwater pics between the two? I'm leaning towards the S400, but dont want to regret the purchase later on. Any advice on this subject would be much appreciated. Thanks in advance. -JB

As Far As I know the S400 (It is A Digital Ixus here in Europe) does not Support Shooting in RAW Format. This is IMHO a major disadvantage UW becaus beinmg able to correct the WB after the Dive is very Important to get a Better Picture Quality.

Simon