If only G15 didn't take-out the ISO wheel and the articulated screen, I might consider upgrading. True, it has made some very good development in terms of sensor and lens but its performance is still comparable to my aging G11 (at least in the lower ISO). The only real advancement (a big one) for me is the lens maximum aperture. I am thinking it will be prudent for me to wait for the next G* or wait for G1X (but I'll miss macro mode so much that maybe I won't consider it) price to go down a little bit. The next G might (I hope) incorporate the very good lens of G15 + the missing articulated screen and ISO wheel (or button?). For those acquiring their first advance compact P&S, G15 or RX100 is a good choice but if we're talking of price vs performance, G15 rocks.
Canon, next time, please keep the S series the pocketable version and the G series the belt-bag version just like with G12 and S100.