[rwfreund]

Although a committed M8 shooter, I bought a D3 recently mainly due to high iso needs, long lens, and macro use.
I have a rather old 50mm 1.4D nikkor that despite a touch of element separation works reasonably well.
What I have found is that I get very usable images at iso 3200, and sometimes depending on subject at iso 6400. The mass of the camera actually helps to damp mirror vibration so I have no problem hand holding at 1/30 sec if I take a bit of care.
I will be replacing that lens, since the loss of sharpness at 1.4 is noticeable, but seems to be corrected at f/2.
With the M8's 1/8000 shutter, I can hand hold to about 1/15 under favorable conditions. I am hoping that the lower vibration of the 1/4000 shutter will increase my hit rate.
The D3 also has a delayed release mode which pauses slightly between mirror up and shutter release. I think that this can also be used hand held without too much bother.
Bottom line in my estimation, I can get files with the D3 at 3200 which compare favorably with the M8 at 640. That is about a 2.5 stop advantage which is major for me.
-bob