Well, kind of. My dillemma was between buying what I wanted (Canon G3) and what was more economically feasable, the S400. Ultimately I got the G3 because I'm probably what you would call a hardcore shutterbug and wanted the fully manual mode.
The main other reason I got the G3 was it's size. I'm never going to leave the G3 in my pocket when I wash my pants. The elph series runs that risk, specifically with me. That may or may not be a problem with you but it's something to consider.
I would say this, if you're not a "hardcore shutterbug" you might want to consider a cheaper model with around 2.0 megapixels. The S400 has four megapixels, thats a lot. Looking through the Canon page however it seems like they don't go much below 3.2 anymore. 4.0 megapixels is big, real big, the quality is super nice but almost too nice. Your average person isn't really going to need images that print at over a foot in length (they're really that big). As an example check this out:
WARNING TO DIAL UP USERS OR THE IMPATIENT IT'S A REAL BIG PICTURE.
http://moremonks.com/cory/small_town_blocks. jpg
***ON EDIT: I realized that posting the whole URL included the picture in my post, it's real big and didn't want to subject people to that if they didn't want to bother. To see it just copy and paste the line and then delete the space before jpg at the end.***
If you're in internet explorer and the picture resizes itself to fit in one screen, put your mouse over the picture, a box with arrows pointing out at it's corners will appear in the lower right hand side of the picture, click on that to see the full size.
This is four megapixels. You can choose a lesser quality (and therefor smaller picture) but I usually don't. If you don't need four megapixels it don't get it and thats about the extent of my advice. Now I'm off to drool over the G5 which I didn't know was out yet.