you may need to put a -.3 or -.6 EC as your regular EC setting.. many, if not all try to over value the ISO to have a slightly underexposed file, Maybe the E-P3 is not that way, and has true ISO settings....
When I owned a Pentax K20D, Canon XT1, Olympus E-510, , that was normal operating protocol, to set the EC to -.3 or -.6
You may try setting the Contrast to -2 and see how it goes, the lower contrast will darken the Highlights a little, and may be enough. And adjust Contrast latter with Curves.