Mother of an active 9 month old baby -- Need an upgrade from Canon S95

My beloved S95 is on its last legs. It keeps giving me E32 error messages and turns itself off.

It's served me well for daily photos of my baby since the day he was born, and I have loved its portability and capability in low light (indoor) situations. I also love its ability to capture shallow depth of field easily on closeups and portraits.

When I upgrade, I'd like a camera with minimal shutterlag, as my son is all over the place now.

I'm hoping to stick with Canon if possible, and my budget is around $500.

I have my eye on the S100 (heard S110 isn't worth it) and the G15. Any other suggestions?