The one and only reason I didn't go with the Samsung NX100 over the Sony NEX-3 was that the current batch of Samsung NX cameras actually suffer from MORE ISO noise than my Olympus E-PL1 and E-PL1s with their 4/3 sensors.
If I'm buying a camera with an APS-C sensor then I want the high ISO advantages of a good APS-C sensor. The first image samples from the new NX200 don't look horrible, but I'm not impressed with the first high ISO shots I've seen from this camera. I suspect the NEX-7 will do better at high ISO even though it's packing more pixels in the same space.