Eos M or Micro 4/3

Obviously, you are the only person who's able to fully understand your photographic needs, so take all answers accordingly.

I'd personally guess that we see a Panasonic GX2 before we see another round of EOS-M glass, but my guess is as good as any other person's.  Whether it has the GH3's sensor or a tweaked version of its current sensor is anyone's guess.

Some people seem to have pretty good copies of the compact X power zoom.  Others don't.  If you decided to go the route of µ4/3, the best bet would be to buy it from a store that offers a good return policy.  As for the 12-35, it seems to be more or less fairly priced for what it is.  Fixed aperture zoom lenses from companies that make camera bodies aren't cheap.  Those that have purchased the lens seem to really like it.

From my own move from Nikon to µ4/3, it's been a difficult adjustment (still am not sure if I'll really commit to the format all the way).  But there's no question that µ4/3 is the only mirrorless system that's really fairly filled out.  They crush Nikon on native wide-angle primes.  They've got choices for telephoto and macro.  2 good fisheye options along with some nice wide-angle zooms.  Still lacking in really high-quality telephoto options, but they're likely to be coming in some form or another eventually.  Flash options probably have a ways to go, especially on the Panasonic side of things (still improving, though)

For now, EOS-M is limited to a body, 2 lenses, and an adapter.  If you want more, it may not be the best choice.