Martin,
The S95 is a superb little camera, producing pin sharp photos in low light. I know of some Pros who use them as back up cameras. The other two are basically replacements to the S95, so should be an improvement.
Also take a look at the Nikon P300 or P310. This has a super fast f1.8 lens, which is incredible in low light, especially when using the cameras stabilization system. They are also cheaper than the Canon. It then becomes a case of which you prefer when handling.