I didn't realize dxomark had released their stats for the RX100, cool. My real world experience agrees with their results, if not suggested that there was a bigger gap. The RX100 was clearly superior to the GF3, even when the GF3 has the advantage of a faster / better lens. My experience was that the RX100 maintained image quality better than the GF3 at higher ISO. That said, the GF3 is not know to be one of the better 4/3s cameras. I owned one briefly as a backup body and dumped it as soon as I get my OM-D. I was very disappointed with it. Of course, the GF3 is a previous generation of the cost contained 4/3s line, so it is not a good representative of what 4/3s can do.
If you compare the RX100 to the GH2, which is the best of the 4/3 that dxomarks has published their results, you will see that while the RX100 has a better overall score and maximum dynamic range, etc... that is due to you being able to shoot the RX100 at ISO 80, where the GH2 bottom ISO is 160. If you look at the graphs, you will find that once you get to ISO 160 and above, the GH2 is typically performing better than than the RX100. When we have done test shoots (or used both in the field), the GH2 was better (to my eyes) as ISO 200, and clearly better from ISO 400 and up. Actually, it was better even when we were shooting the RX100 at ISO 80, and the the GH2 at 160, but the GH2 was using what I expect is a better lens.
My experience is that the newer 4/3s such as the Olympus OM-D (which dxomark hasn't release data on yet) have sensors that out performs the GH2 by 1-2 stops, I expect that what these cameras' data goes up, you will find they have better sensors than the RX100. Add to that a wider selection of lens, and you have something that clearly trumps the RX100 on image quality. On the other hand, the GH2 or the OM-D, or the G5 don't fit into your pants pocket.
The RX100 is a remarkable little camera, and I think close to ideal for the range of pictures I typically take backpacking. The only camera that might be better (since most of my pictures could be classified as either landscape or portraits in environment) would be the Sigma Merrill DPx... which I will ... must... resistant. I am trying to simply life, and I really don't need another camera.