Cliff
Your reply is taken in good spirit, and I didn't intend to to argumentative! (and thanks for the compliment regarding my X100 images, I have to say that this forum is the main reason my photography has improved).
There are some simple rules of physics here, and higher ISO's (effectively sensor gain) really do work better on a bigger sensor (physical size). And yes modern sensors are getting better and better, however you only need to look at the latest Nikon FF (read Sony!) sensor offerings to see how far high ISO is progressing. But the laws of physics dictate that a FF 16MP sensor (assuming that it doesn't have interpixel gaps the size of the moon) will receive more light at a given aperture setting than a 16MP micro 4/3 sensor, approx 4 times as much light). That said given comparable optic quality and a comparable subject/lighting then in many circumstances the IQ will be comparable. And I agree high ISO situations are few and far between for most photography.
I've never really looked at the Olympus MFT camera options, I went DSLR -> X100 -> other Fuji Mirrorless. Maybe they are something that I should investigate a little further, one thing I have discovered though is that you need to be very careful with legacy glass, as its often not capable of resolving sharply at all aperture settings, that said there is some known quality glass from Olympus, Minolta and others which can be had at very cost effective prices. Yes, the Fuji glass on the whole is expensive, but Fuji have a very good reputation for optics (I work in machine vision, and their C-mount offerings are amongst the best), and none of the X-mount lenses I've used have disappointed.
Back to the OP's original point the EOS-M (especially with the 22mm pancake or kit zoom), may be a good lightweight option and the EF adapter will allow him to use his existing Canon lenses, but given the fact that he is in 'sunnier' part of the world than most of us, he may find the lack of viewfinder a challenge in some lighting conditions.
