For ME, and judging by what type of camera you seemed to indicate you were looking for...I'd personally think the Fuji X10 would be going to too small a sensor. It's quite good for a small sensor, but not going to handle the real low light stuff quite as well.
Well, I've been looking at the noise comparisons at high ISOs, and the X10 seems to do favorably well. The reason I came back to it was because its lens is much faster than the G1X or the RX100 at the long end, which should offset its small sensor disadvantage. Sure, I can't really get shallow DOF, but I can't do that with the G1X or RX100 either, but at the same time, sometimes I don't want to. I'd like to use this thing mainly for street photography, and even at f/2 the X10's hyperfocal range is really short. On top of that, I've heard good things about the Fuji X-cameras' JPEGs. I like shooting RAW with my DSLR, but in this case I really do want something that requires minimal hassle. Having manual exposure is good, but for a travel camera that will accumulate thousands of shots, I don't really want to be doing post processing on it. That's why I'm leaning more to the X10. Plus, it's the cheapest option.
I'm really curious to see the f-stop progression on the RX100. One of the reasons the G1X is dropping on my list compared to the X10 is because its fastest f-ratio in the middle focal lengths where I'm most likely to use it is pretty mediocre, only f/3.5 or f/4. I'm wondering if the RX100 is similar.
The G1X sensor is excellent, but for me I think the body is too bulky and large...more like that of a superzoom camera. If compactness including pocketability is not a concern at all, then I can't see if you are going with a larger body not just going for a NEX or OM-D and get the additional advantage of a growing lens system.
The issue is price. The G1X is only $700 on Amazon. The NEX-5N body alone is about the same price as the G1X. And the OM-D E-M5 is $1,000 for the body alone. I'd love the NEX-5N, but any lens I get for it won't have the same range as the G1X, will likely be much bigger, and make it much more expensive.
But, as I said, right now the G1X is #2 behind the X10.
The X100 would certainly meet the low light standards with an excellent sensor, though only you could tell if you'd feel limited or restricted with a relatively wide fixed lens only.
Yeah, I think my fascination with the X100 is mostly for its novelty. There's no doubt it takes amazing pictures, though. It seems like it would be the best option for street photography. In that sense, it's not really in the same race as the other options I've mentioned. With the G1X, X10, and RX100, I'm looking for a general purpose camera that can take the same range shots as my DSLR (60D w/ 24-136mm EFL), just more portably. With the X100, I'd be getting it as a camera that does a few things really, really well.
Anyway, I'm still torn.