I have the same situation on my G3 and Olympus XZ-1 with VF-2. Neither EVF reflects the reality as far as colours and brightness. However, sometimes I find it to be an advantage when the EVF is brighter because I can see the subject better.
With a few days of experimenting with my new E-M5 I have noticed something I find strange.
When I use the EVF to compose a picture I see bleached and washed up colors (for instance when I am outdoors in aiming at trees and other nature scenes in evening sun). I take a picture and see the result for half a second. The resulting picture has much nicer and warmer colors than live view. I have the Picture mode at default "Natural" which I believe is influencing the colors of the resulting picture.
I know it is possible to adjust things for the EVF in the menu, but I find it very strange that the resulting picture looks good through the EVF but the Live View is much worse. If I adjust the color settings in menu, would that not change how I see the resulting picture also? I never experienced a big difference between Live View and Resulting picture viewing EVF with my Panasonic G2. Or is this the a result of that Olympus has a superior JPEG handling?
Any similar experiences or tips how to get around this?