Stick with Canon Powershot or try something new?

[demooderew]

:?Hey folks, I originally started with a Powershot S230, then an S400, and currently have the S500. Out of the 3 I liked the S400 the most, it seemed to function the best. Now I am in the market for a 7+ mpix compact and am wondering if anyone has comments on the SD500 or SD550 regarding the following:

#1. Focusing time, is it faster? The S500 I have is a dog on the focus, I have to tell everyone to wait for the flash all the time, missing some candid shots due to the slow focus with regularity.

#2. Low light focusing, is it better? My S500 is horrible with night shots. Canon switched from a white assist light on the S400 to a red one on the S500, which I think performs very poorly. It often takes multiple tries for the camera to get a focus lock in low light, even dusk situations.

#3. Finding the correct subject in the photo, any better? My S500 seems to find the wrong subject a little too frequently.

I've always been a Canon fan but I've always been intrigued by cameras that friends have owned, Casio, Sony, Pentax, etc.

The S500 has left a bad taste in my mouth, is it just a fluke?, do I jump ship or stick with Canon? Is the SD generation worth a try?

Thanks

-Tom