This field-review is long, so I have divided it into three parts:
Part 1: Introduction and first impressions and handling.
Part 2: Shooting macro, lens selection, diffraction, autofocus performance and modes. Below.
Part 3: Shooting wide angle, lens selection, high ISO, dynamic range and conclusions.

MACRO
Macro shooting is one area where I felt the D3 would have some advantages and some disadvantages compared with a DX format camera. It turned out that way, but the differences were harder to spot than I expected.

I used the D3 with three macro lenses: Nikon’s 60mm AF-D and 105mm AFS VR and Sigma’s excellent F2.8 150mm macro lens. Wetpixel’s James Wiseman has been championing the Sigma for ages as an ideal macro solution for full frame cameras, particular when combined with Canon’s 500D dioptre. Basically it gives the same field of view as a 105mm gives on DX, and angle most find so suited to so many underwater subjects since converting to digital.

The FX sensor on the D3 returns the 60mm to its full angle of view. A main weakness of DX cameras for macro was that the 60mm had an equivalent angle of view on 35mm-film to a 90mm, which is a bit long for some subjects. This has driven quite a few of us to experiment with other lenses (such as Tokina 35mm, Sigma 17-70mm, and fisheye-teleconverter) on DX cameras to fill the gap. However, while on the one hand it is great to have the old 60mm back, on the other, I found myself surprised by the lack of versatility this lens offers on FX.

On DX, the 60mm is definitely the go-to focal length for macro flexibility. However on FX, despite being able to focus to 1:1, it is not as flexible a lens as I have got used to on DX. Both in Canada and California, my DX shooting buddies would be able to shoot a much wider range of subjects than I could with the 60mm. It just happens that nudibranchs sized critters are just the wrong side of the useful cut-off for this lens on FX and just the right side on DX. To shoot these subjects well on FX you need to get down close to 1:1, where the camera to subject distance is so short that it compromises lighting - I am talking small differences here. Of course it is still possible to light subjects at 1:1, I just feel that you do not get the same quality of lighting as you would on a longer lens at the same subject magnification. And who wants to take compromised images.

Of course what you loose on the swings you gain on the roundabouts. On FX, the Nikon 105mm VR becomes much more of the all-rounder, particularly when paired with a 5T dioptre. This weak dioptre shortens the minimum focus distance of the lens should you need to get closer than 1:1, without restricting the maximum focal distance too much. In fact the 5T would be a great teaching aid. If something is too far away with the 5T it is probably not worth shooting. Annoyingly the standard Subal 105mm VR port does not provide room for useful supplementary lens. I used it with my own port.

The 150mm with the 500D is something of a niche lens on DX. I use it regularly to achieve shots of common macro subjects with a fresh perspective. But I would be the first to admit that the difficulty of aiming a lens (with a film equivalent focal length of 225mm) generally means that I get a much lower hit rate than other macro lens. On FX I would agree with James that this lens becomes a mainstream lens, with an excellent return rate. One downside of the 150mm is that it made the Subal housing negatively buoyant and nose heavy, although Todd Mintz kindly lent me his buoyant StiX arms, which solved both the buoyancy and trim problems.

Perhaps my most surprising finding was that all three of these lenses were highly useful. On DX I could contemplate leaving the 150mm at home unless I had specific images I was after. On FX I would want all three with me on most shoots.