Well, I succumbed and bought an OM-1 - it's primarily a land camera for the foreseeable future. That is to say I'm not planning on taking it UW at this stage.
So how is it??? In no particular order
AF is a big step up it snapped to focus on subjects where the EM-1 II just hunted in low light
new high res EVF is excellent and layout of info is good- keeps out of way of image
ISO3200 is very usable. The AI based noise reduction in OM Workspace does a nice job
Noise is subjectively better then EM-1 MkII
Bigger battery is nice with 25% more capacity
Subject tracking works pretty well
The better in body stabilisation is great.
Body is very solid in the hand feels very high quality - the sort of feel you had with the Canon 1D - 1Dx series cameras
Some samples
Common Bronzewing with 300mm f4/1.4x 1/80 @ f8 ISO800 handheld :
http://homepages.ihug.com.au/~chrisx2/i ... ewingL.jpg
The bronzewing was processed in Capture One Pro and PS, no noise reduction apart from standard applied in Capture One conversion.
Did have any subjects needing high ISO so in best traditions of DPreview of old I took a photo on my cat in low light indoors.
1/60 @ f8 300mm f4 ISO3200:
http://homepages.ihug.com.au/~chrisx2/i ... xxie_L.jpg
on this shot the OM-1/300mm f4 snapped to focus but the EM-1 just hunted and refused to focus.
And here is a 100% crop comparing Capture one Noise reduction (standard) and OM workspace AI based NR :
from image above:
http://homepages.ihug.com.au/~chrisx2/i ... ompare.jpg
To compare noise performance with EM-1 MkII, I took shots of a dry flower arrangement at ISO3200.
this is about 50% of frame:
http://homepages.ihug.com.au/~chrisx2/i ... SO3200.jpg
and is here is a EM-1 MkII/OM-1 comparison, 100% crops both capture one processed:
http://homepages.ihug.com.au/~chrisx2/i ... SO3200.jpg
Subjectively to me the noise on the OM-1 is better - more even without the clumpy noise from the EM-1 II, using OM workspace should improve it further.
All in all seems like a great camera, obviously not full frame but really suitable for my uses.