I would say that, considering the size and price, a NEX-5 with the Zeiss ZM C-Biogon 35 f2.8 will rival just about any combo out there. It's a terrific, small, bang-for-your-buck setup. Add a Nokton 35 f1.4 for lowlight work, and you've got a great one two punch for standard lenses.
I've ended up selling all of my fullframe DSLR gear, because the little NEX-5 with various rangefinder lenses gets the job done in a tiny package.
I agree wholeheartedly with the NEX providing the best IQ for an "always-pocketeable" combo. There is a wealth of top-notch, light and compact glass that will fit the NEX: Leica M, Zeiss ZM, Voigtländer, Contax G... Plus the fact that NEX bodies will continue to evolve and improve much faster than Leica for much less money.
More specifically, I did a shoot with my 5D II and Zeiss glass, my NEX and Zeiss, and a friend who shot a 5D II and a Leica M8 II. At another shoot, a friend had a 5D II and a M9, and we compared IQ. No doubt, the M9 is a terrific image maker, and some Leica lenses appear to be superb as well, such a Summilux 35 ASPH. But the difference in IQ between the NEX and the M8 is not clearly in the M8's favor. Direct comparison is not totally straightforward because of different crop factors, and the many pluses and minuses go both ways, but, overall, I wouldn't trade my NEX for an M8 II.