There is little first hand information about the Casio Z60 and Z600.

I did find some sample photos for the Z600 and to me they looked soft, about the same as the Canon SD450.

I could not find any sample photos for the Z60.

I would wait for some reviews to show up before deciding.

While you are waiting, take a look at the Olympus Stylus 710. The lens on the 710 is sharp.