In a few days, I'll have both the GX1 and the G3. Then I'll know more. I bought my GX1 a couple of weeks ago and just took it and my GH1 on a seven-day river trip in Utah. Between photographing and rowing the raft, I managed quite a few photos with both these cameras, but I haven't looked at 'em yet. Anyway, I came home wishing I had two such highly regarded cameras with the three-generations better, 16 MB, sensor. Plus, I really, really missed the swivel LCD that I love on my GH1! My opinion of eye level finders is low, and I hope I never squint into a peephole again for as long as I live! But I know that bright sun may dictate a different choice, and it's there if needed. That internal image processing is reported to be much better also made the G3 attractive.
So.... Today I ordered the G3 body while it was on sale. I don't know what I'll do with my GH1, but I'll have the G3 and the GX1. Why have multiple cameras? I have several m4/3 lenses, but I really detest changing lenses on a digital camera lest a speck of dust get onto the sensor. On the river, I kept my Olympus 9-14 mm lens on my GX1 and my 45-140 mm lens on my GH1. The latter lens will probably end up on my new G3, and my GH1 will end up who knows where? Probably with my 14-42 lens on it. I believe I'm moving ahead.