OM-D RAWS appear to beat Panasonics
 

At 1600 and 3200, the yellowish mottling is apparently on the
Panasonic G3 and GH2 raws, but not so much on the Olympus. The more
gold tint of the Olympus raw might have something to do with this.
The Olympus jpegs as usual, are much better.
The GH2 appears to have slightly less luminance noise and Sony's NEX-7
has more noise at those ISO's than the other three.
RAW contrast is higher in the Olympus, which could mean (uncertain) a
more compressed DR.
Olympus rendering of reds seems better, with the GH-2's being
pinkish.

http://www.dpreview.com/previews/olympusem5/7