G15 flash ISO

I just received my G15 and am starting to familiarize myself with how it works in comparison with prior higher-end P&S cameras.

One of the first things I've noticed is that by default (in Program mode), when the flash is activated, the ISO is always 640 (assuming the ISO is set to 'Auto').  I was quite surprised by this.  Previous cameras (all Canons) I've owned all have the default flash ISO at 200.

Is the G15's performance at ISO 640 so much better than earlier cameras that it makes sense to have the default here at 640?

I've also noticed that I can't seem to change that default ISO.  Of course, I can set the ISO manually to whatever I want, but if the ISO is on 'Auto', with flash on the ISO will be at 640 and can't be changed.  Is the experience of others or am I missing something?