Yes, different cards with different stock speeds and different cooling solutions will change the power draw slightly. For example some pre-overclocked cards use slightly higher voltages on memory/core to achieve the stability. Also on the x1800 series for example, different revisions of cards had either 5 or 6 phase power i believe.
As for OC3D measuring power consumption, this is not something we are planning on performing at present, but if there is a need for it then we'll certainly look into getting the equipment.
However, on the PSU side of things, we will very shortly be measuring: Power Consumption (for Efficiency), Noise and Heat. The key thing for us is making sure that all of these tests are performed under the same conditions, so results are comparable.