D7000 or D600 in incandescent light?

Hi,

I am in a bit of a dilemma - I would like to take photos of stage performances under red/white light with a prime (normal settings are e.g. f2.8, 1/250-1/500 at iso 1000 to 2000 ish) and would like a camera that I can trust to focus reliably. It would be nice if the camera was also quiet, as the venue is rather small. The photos have to be of good enough quality for the local "What's on" to print (300 dpi minimum apparently), so not sure of a u4/3 is good enough.

Focus fine tune is essential for me as the Nikon DX workshop does not appear to do a good job. My history is that I had a D5100, which was a nice enough camera, but had its fair share of focus problems, including back-focus, then front-focus after Nikon "fixed" it the second time.

So, my dilemma is whether to stick with DX and get the D7000, which seems to be a bit of a diva camera with a history of users having focus problems, or go for the considerably more costly D600, which seems to have dust and oil problems, but no reports of focus problems (so far?).

I'd rather pay the extra to have reliable focus, even if it meant dust problems, than have autofocus problems again. But would I get more reliable focus under the above conditions for the extra money? My impression is I would, but is this correct?

I had also considered the D700, but it is not much cheaper 2nd hand than a new D600 at the moment and it apparently has quite a loud shutter.

Any imput gratefully received.