Sat 12-Oct-13 06:46 PM | edited Sat 12-Oct-13 06:48 PM by Ferguson
I had a D300, and I kept it for a while and never picked it up again. I loved the D300, it was a great camera, I had it from the first weeks it was onsale, but the D800 was just better in all regards. If I wanted reach the DX crop area on the D800 was better than the full D300 image.
The D700 I can't comment on, but I suspect you will find the same.
Keeping either (I'd opt for the D700) for a second body (if you are a two body shooter), or for a backup, is another matter.
Left focus - I did have mine fixed. I don't think you can get an adequate feel, unless it is a horrible case, from a dealer in the store. I'd buy from someone with a 30 day return policy (e.g. B&H) and see what you find at home.
You've probably done your reading and know there's all sorts of controversy around this. It was months before I was convinced I had the problem, and it only really showed up when I did a bunch of portraits (which meant I was shooting at very wide aperture on the left or right focus point to hit the eye/face). Testing showed it clearly but it required some focus charts, tripod, and time to do some really careful shots.
Perhaps more importantly (and here is another more controversial aspect), I think the D800 requires fine tuning on most lenses. And if you DON'T do the fine tuning, you may find you have a "left focus problem" and you really don't. So I recommend doing that first, if you are seeing an issue. Example (contrived), suppose the camera really needs a +10 on the center, and your left focus is off +5 from the center (which by the way is probably acceptable and not a problem).
This means at 0, your left focus is off +15, and center off +10. That might be enough cumulatively to convince yourself you have an issue, since maybe 10 is "ok focus" but 15 is noticeably blury. Get the center right, and the (slightly off) left may be fine. They will never, ever be all perfect, what you want is for left and right not to be radically different from center.
Nikon fixed mine just fine. I'd probably return one during a return policy if I had the issue, but at least for me, it was not that painful to get it repaired under warranty. I picked a time when for a few weeks I wasn't shooting, sent it in, got it back, no big deal. I would also hope by now Nikon was no longer shipping bad ones, but who knows. Buy from somewhere like B&H (if you are in the US) where you can return it, and you're doubly covered.
It is not a problem worth avoiding for the left focus problem.