I don't shoot m4/3 because of size

I was just running the dpr comparator on the Sony A99 test, and even given the limitations of that test (the studio image doesn't really show off the latest FF sensor to their full advantage), it was interesting to see the EM5 keeping pace with the big guys at the ISO's that most of us tend to use. True for jpeg and raw. This would have been unimaginable a few years ago.

The other interesting revelation was how poorly the D600 did - image was not at all sharp. Don't know what to make of that - were they using rubbish for glass?

Sensors are peaking out in capability. They are already so good that further improvement tends to fall into the 'very seldom used' area. How often would one use ISO102400, or put 32mp to full use? For most of us, not that often, if ever. DR could be better, but until someone comes up with a simple, easy to recite number for that, the gearheads won't clamor for it. Even the APS sensors don't show much improvement over a 4/3 sensor, nor do they show that much improvement over their predecessors.

That leaves only one area where serious improvement can be seen - size. And there, M43 delivers. Given current technology, M43 hits the 'sweet spot' - you gain a lot in size, but you don't sacrifice much if anything in performance. Above M43, as in NEX, the lenses get big but there's no substantial gain in capability. Below M43, as in V1 or Q, performance and capability are compromised. Future sensor improvements may negate that, but as of today, M43 is about where one wants to be if they want smaller without compromising capability.

Personally, I got into the EM5 for the better sensor - mine tends to have HG or SHG ZD glass on it, which negates (somewhat) the smaller size. But, it's nice to have the option to pop on the 45 1.8 or 12-50 and go very small. Even with a larger 4/3 lens on, it's not quite the attention magnet that a full size dslr body is.

Is M43 'better' than the larger cameras purely on performance alone? No it isn't, but it's close enough, and the size is a real bonus.