It's pretty clear that the TS is looking for a premium compact, and he don't want to change lens, so EOS-M is out.
As for the S110, there are plenty of other competitive premium compacts out there. Not anti-Canon, and in fact, in awe of the fact that they were the ones who came up with the original premium compact in the S90 (together with the Panasonic LX-3). But over the years, they seem to have been resting on their laurels, offering bit improvements to the S-series in the S95 and S100. Now, its competitors have all caught up, from the 3-times larger sensor Sony RX100, to the stylish yet with larger sensor Fujifilm XF1, to the amazing fast lenses of Panasonic LX7, Oly XZ2 and Samsung EX2F (it comes w a swivelling screen too!). Apart from the slightly longer optical zoom (which aperture is a 'slow' F5.9 fully zoomed out), I was really quite disappointed when the S110 was announced recently.
and reliable ? On what, the basis of the Canon brand ? Have people heard of the lens error issue in the S100 ? I know of plenty of people w this problem and had to bring their camera back to Canon to get it fixed. hope that Canon would have learnt the lesson for the S110.
out of your list, the RX100 is definitely the best (in my opinion) - afte trying out a few high end compacts, the RX100 is the best for me. its very compact, has the biggest sensor, highest MP count, and i think offers the best IQ - although in its compact size, u might miss a few controls etc..and its control ring around the lens is not as great as competitors
but like daredevil mentioned, the fuji XF1 is another great option, for over US$100 less than the RX100. so definitely check that out, it looks very impressive (and i love Fuji's manual zoom ring)