There is a review of the Canon G10, Nikon P6000, Panasonic Lumic LX3 (almost identical to the Leica IIRC), Ricoh GX200 and Sigma DP1 in this months Photo Pro Magazine.
Basically the summary was none (other than the Sigma) compares to DSLR quality at any ISO higher than 200.
The ratings were
Canon G10
Build Quality = 5
Usability = 4.5 (let down by shutter lag)
IQ upto ISO200 = 4.5
IQ at ISO400+ = 3
Nikon P6000
Build Quality = 5
Usability = 4 (pleasure to use but slow write times, especially RAW [about 5 seconds

])
IQ upto ISO 200 = 4
IQ at ISO400+ = 3
Panasonic Lumix
Build Quality = 4
Usability = 4.5 (Good but Nikon and Canon beat it)
IQ upto ISO200 = 4
IQ at ISO400+ = 3.5
Ricoh GX200
Build Quality = 4
Usabiliy = 4 (a little slow and dated looks)
IQ upto ISO200 = 3.5
IQ at ISO400+ = 3
Sigma DP1
Build Quality = 3.5 (solid but very bland)
Usability = 3.5 (good but could do better - remember it is a fixed focal length)
IQ upto ISO200 = 5 (mind blowing)
IQ at ISO400+ = 5 (difficult to spot they are high ISO)
My additional thoughts on this is that the race is between the Canon, Panasonic and Nikon. The Canon G10 is quite a bit larger than the Panasonic and Nikon, the Panasonic has a smaller zoom range (24-60) compared to the Canon (28-140) and (Nikon 28-112).
One additional thought is that for a Nikon user (like the OP) the Nikon does have a Nikon dedicated hotshoe on it so (theoretically at least) you can use your SB400/600/800/900 on it and get iTTL metering.