Jono knows I have some sympathy with his 'predicament'
Personally, I use the Leica M240 (previously M9) and the EM5, and I'm in the market to replace the Olympus. I have been with four-thirds and m43 for several years, but the M files have spoiled me. Fully aware not everyone will agree, but from a handling and file processing perspective my own opinion is that the M240 is a step change up from the M9.
And for me that means the gap between my Leica and my Oly has widened...
Godfrey, I have every respect for your opinion, and bear in mind I have neither the latest incarnation of the Only, nor the Sony, but I find this amazing to be honest:
....Examining the files out of the A7 and the E-M1, the file quality on noise/DR/acutance etc is quite comparable right up to ISO 6400, so the output of both processes very similarly and looks consistent when presented together...
My own experience, and the motivation to switch, is that Oly files quickly fall apart under processing. I enjoy gritty files sometimes, but don't expect to see noisy blue skies at base ISO.... which is indeed what I see with the EM5.
Anyway, back on track.... seems to me everything is a compromise. Isn't that why we have all these brand and camera choices?!
Mike