Some randomly assorted thoughts on m43 cameras based on my own experience:
Panasonic menus are easier to deal with than Olympus (used both, panasonic was a hands down win, far more intuitive).
Olympus in camera JPEGs are arguably better than Panasonic, especially if you use the art filters such as sepia, BW, moody, etc. Raw is a tie.
Panasonic video tends to be better than Olympus, especially in the higher models and even more so when used with Panasonics HD lenses.
Panasonic bodies tend to be better at correcting for chromatic and spherical aberration artifacts, especially with panasonic lenses.
The OLED screen on the E-P3 is better than any Panasonic offering if you require the best image for composing your shot or high quality playback in camera.
Although interchangeable, m43 lenses work better on their respective manufacturers bodies, particularly wrt focusing speed and inbuilt correction of lens aberrations.
If you are after a small camera for biking and can afford it I’d personally get the Panasonic GX1 with powerzoom 14-42mm. The OH has a GF2 with this lens and it is the best compromise I’ve seen for portability vs. picture taking prowess. The GX1 would make it more so. If you want a viewfinder then the G3 is similar to the GX1 in performance and handling but has a plastic body. I personally don’t like the ergonomics of Olympus PEN series cameras (E-P3 excepted) or the smaller Panasonic offerings but I have big hands and like viewfinders.
I think the GF3 is too limited as a “real” camera, for not much bigger size I’d rather get the GX1/G3 and have much more control, better pics and ergonomics. If you can cope with the rather tiny size the new GF5 may be a good middle ground although it lacks features a full camera would (should?) have such as a hot shoe, iso button, etc. Long lenses on the GF3/5 and smaller PENs get unwieldy due to the body size/grip.
At the end of the day go into a shop and try some, it’s the only way really.