Just a quick heads-up . . if you're looking for image stabilization (likely not, eh?), Panasonic does it in the lens, Olympus in the body. So, if you put Panasonic on an Olympus body, not sure if you could turn the lens IS on or off? Others will know.
On image quality - that is an important factor for many. I believe that a lot of the potential for acceptable 4/3" quality lies in the processing, both in-camera and in post. The (for screen-viewer moi) enormous image sizes of 4000x3000px+ do give significant gains (e.g. noise, acutance) if downsizing is your bag.
For some reason, that doesn't look right to me but then I tend to ignore the "equivalent mm" thing. What I do know is that a bird shot several yards or meters away will appear at either image plane exactly the same size in actual mm. So, if the birdie is as wide as the sensor in a 4/3" shot, it'll only be half the sensor width in a "35mm" sensor shot. By looking smaller in the latter shot, the same lens gives less apparent magnification in the sensor output.
Therefore, would not a "250/4" look longer on a smaller sensor?