What lens were you using? What lenses do you normally use for your D3S?
If you're typically shooting with a Nikon 70-200/f2.8 - a lens which sells for $2000-2800 now, depending on the version - did you consider that you might get better results with a comparable Olympus lens like the 35-100/f2 which you can still buy brand new for $2000? That would drop you down 1 stop of ISO compared to your D3S, and would give you one additional stop of DoF as well. Another option would be the $750 Olympus 75/f1.8, which is incredibly sharp.
Or, if you typically shoot with a Nikon 300mm/f2.8, a $5500 lens, have you looked into the $2400 Olympus 150mm/f2?
Given how much cheaper the body is than a high-end Nikon, you might do well to invest in some of the better glass. It is also typically available used for half the new asking price, sometimes even less.
Not to mention, you can also downsize the 20MP files from the E-M1 down to 12MP to match your D3S, giving you 1/3 stop less noise.
Between faster lens choices and downressing of files, you should see much closer quality than simply trying to match the settings that you are used to shooting at.
Thanks for the great analysis. I was using the Olympus 40-150 f2.8. I suppose I could invest in more Olympus glass, but I have only so much money to go around.
I know a lot of people have suggested primes, but for indoor, fast court games where I'm focusing on the player primarily, a zoom is much more practical as the players move erratically around the court. I've had this discussion with other sports shooters and news photographers, and we've reached pretty much the same conclusions.
Your suggestion to downsize (and others on how to post process) are something to consider. But on a practical level - and again, this is just how I work - I prefer something that's much faster and less complicated when I'm shooting sports. Unless it's critical, I shoot JPG only: easier to manage files, smaller, more readily processed and accepted by the end users.
For example, when I shot the Canadian University Women's Basketball Finals, I shot 3 games per day, for three days straight, with only an hour inbetween games. In that hour, I'd review 500 to 800 photos, select the best ones, edit quickly, and then fire them off to the tournament organizers so that the images could be uploaded to the host university and the national website. So, the less time it takes for RAW to JPG conversions, downsizing, etc., the better off I am overall; preferably, I don't even need these extra steps.
The D3s is great: big, fast, lots of power. But it's big.. and at 12 MP resolution, you can only crop so much if needed. That's why I was so intrigued by the Olympus. I have the EM5Mk2, but that was pretty much for travel and street shots. Along comes the EM1Mk2 and its 18 fps, 20 MP sensor, lighter weight... too good to not give it a serious try!
Hey, you never know... maybe the EM1Mk3... :-D