I got an optio S4 for $350 so you should be able to see some serious price dropping on the original S model. Disadvantage of Pentax is that it is using special battery which means that if you run out you are stuck. Also because of different lens design there is small distortion in the corners. So reason for getting Pentax is only its size. Canon cameras are great. The model you chose is very comparible to nikon. I like macro lens and meetering on nikon more but that's because I'm used to it. One cool thing about Canons is that they usually make nice underwater housings for fraction of the price. That's something that is nice to have if you spend a lot of times outside.

Matt