Peter,
the m43 cameras I had from Olympus (EP2 and EP3) were both not really better WRT noise than the V1.
The GH2 I also shot for a while had a much better noise performance although it uses a 18MP sensor. I assume that the new OMD, which uses a 16MP sensor (similar to GX1 and G3) should also do better, but still has to prove.
What I like about the V1 is the overall ease of handling (for me) and that the lenses are pretty small. Especially the 30-110 is a real marvel.
What I did NOT like from m43 was the plastic finish of the kit lenses, especially with the EP3. Maybe this improves again when the OMD and kit zoom and other "high end" m43 glass hits the market. Anyway that system will end up much bigger than the 1 system from Nikon.