Is Canon announcing something Aug 22?The RX 100 is more expensive but it does have a larger more advanced sensor and therefore would produce a higher IQ. If I were you I'd wait untill the 22nd to see what Canon has up their sleeves next, or at least until Photokina on the 18th of September to see if there's an update on the S100. In the meantime you can save up some cash in case they announce something really tasty like a G13. If they don't I'll be going for the RX100 it gets such good reviews.
Apparently rumour has it that there will be an Powershot announcement on the 22nd of August we have no idea what it will be.