High-end compact cameras (S-series Canon): is the better IQ parallel to the extra $ ?

Good point. Ironically, the progress manufacturers make in finding software sollutions for hardware limitations automatically makes the difference between superior and lesser hardware much smaller.

On a side note:

I have to make a second thought on the hardly any difference with studioshots claim some posts before. With the X100 (Fuji) you indeed do see a signicant difference at higher ISO values. But then again, that is at pixelpeep level and one can question if regular use and smaller prints will benefit from that (and it would justify the outrageous price tag).