Another thing to consider is the quality of Nikon's FX lenses vs their DX lenses. As I look through the lens tests on the German website PhotoZone.de, and compare the Nikon 105mm f2.8 VR Micro-nikkor vs the Nikon 85mm f3.5 (non-VR) Micro-nikkor, the resolution results they show indicate that the 105mm f2.8 lens out resolves the 85mm 3.5 significantly (by about 20% or more) at the apertures (f11-f22) that would be most useful for macro shooting. Comparing Photozone's test results for the Nikon 16-35mm f4 VR vs the 10-24mm f3.5-4.5 (again non-VR) the resolution numbers again favor the 16-35mm by about 25% at most apertures and focal lengths.
This is not surprising. Nikon considers FX their pro format. The FX equivalent lenses are more expensive and physically larger. And better optically. So if you want the best image quality from your Dslr, FX is the way to get it.