Thanks. The reports out there on how good the EM-1 is on continous AF are varied. The best I've heard is that it's on par with the D200, which if true would put it about 1-2 generations behind the 7D. Thom Hogan also provisonally rates it better than most other mirrorless options but below the Nikon 1 series. Perhaps not surprising, I'm told Oly SLRs were never terribly good at C-AF and in any case it'll take a lot to match Canikon's expertise in that area.
All that being said, I'm expecting the EM-1's C-Af to be leaps and bounds better than the EM-5 (not that that's saying much) and usuable for basic tracking. But from what I've seen on thr net, those looking for great BIF capabilities have been disappointed (though IMO they were expecting too much).
Have an em-5, two gh3's, Canon 1dx, Nikon D3 and obviously on tracking nothing focuses like the 1dx, next the D3, next the gh3. The gh3 actually is quite good, unless your shooting fuel dragsters or 100meter track, but the gh3 does well, even in video.
Regardless I use the 1dx mostly for stills, the Gh3's mostly for video, the em5, mostly because I just like it and would buy an em-1 in a heartbeat if it would track focus, especially with the legacy 43 lenses, as I love the 150 f2.
In fact I don't think they should make any 43 lens slower than f2 but that's just me.
I do know on slow tracking with the em-5 it focuses so fast on single af, that I can touch and release, touch and release and hit it most of the time.
I really think Olympus should have produced an optical finder version for the pro line of 43 lenses, but I guess the market just wasn't there. It's a shame because those older lenses are very nice.
To note; at first I found the em-5 to be a somewhat non intuitive camera to work, but lately have used it a lot, worked around it's quirks and think it's a great little camera.
Also in regards t focus one thing I've noticed on the gh3 and the em5, on single autofocus they will lock on in virtual darkness, or darker than I will ever shoot.
If you can find anything with contrast on the image, in very low light they really lock on.
With the new Sony A series, micro 43 has a challenge. Now they can't just compete on size and cost and they can't just compete on 3rd party lenses, because the A series will take a lot of lenses. Though it shouldn't matter, the em1 compared to the Sony A looks purposeful and well designed and the A looks a little lego block simple.
M43 needs the same focus ability as a dslr, especially olympus as they are pretty much a still centric camera with limited video.
That said, I think the quality from these m43 cameras is very good. A little better than my leica m8 in detail and noise probably 1 stop down from the Canon 1dx, though if done right you can get more than a stop from the lenses with the same depth of field, so it would be a wash, if all the lenses were faster and the focus was equal to optical view finder cameras.