Smaller sensor cameras will have a deeper Depth of Field (DOF) for a given lens focal length. This can be an advantage if you want deep DOF (for landscapes) but also a disadvantage if you want shallow DOF (for portraits). Achieveing shallow DOF on small sensor cameras is a challenge but has led to the release of a number of large aperture lenses for the Nikon V2, SONY NEX et al. See my recommendations above for lens examples.
It turns out, if you do the math, that for the Nikon V2, for a given lens focal length & shooting distance, there is a 3-stop difference required to get the same DOF. For example, f/8 on a D800E would require f/2.8 on the V2 to get the same DOF. An f/4 aperture on the D800E would require f/1.4 for the V2. F/2.8 on the D800E would require f/1 on the V2. To date, no lens exists with that aperture for the V2.
Despite these differences, a given aperture setting on the V2 and the D800E lets in the same amount of light (same exposure, all things being equal. Thus, if there is a 3-stop disadvantage with ISO (S/N), there is a compensating 3-stop advantage in which aperture gives the equivalent DOF. This is illustrated in the diagram below.
Here's how to interpret this chart.
1. For good quality prints, the V2 should operate from base ISO (160) to 1600 max. The equivalent ISO range for the D800E is 1,280 to 12,800.
2. For the D800E, ISO <12800 will yield much higher detail than the V2, at lower noise. Thus this is the range if you want prints > 8X10 @ 360dpi
3. Maximum aperture lenses for the V2 are ~f/1.4. This corresponds to f/4 on the D800E. Thus a good range of apertures is between f/1.4 and f/8 (where diffraction starts to degrade the image). The equivalent aperture range for the D800E is f/4 to f/22.
4. For the D800E, apertures wider than f/4 will yield shallower DOF than the V2.
Thus operating the cameras in the range: V2 - ISO 160-1600, f/1.2 - f/8 will yield identical (printed) images to the D800E operating in the range ISO 1280 - 12800, f/4-f/22. Images should be no greater than 8X10" @ 360dpi.