With DSLR's I find that I need a faster shutter speed for the same focal length as I needed to use in times past with 35mm film cameras. This is especially true for 85mm and longer lens where there is increasing amounts of image magnification. This is where VR truly can be essential for wedding photography in particular.
Keeper rate varies even with VR and part of this is that subject movement is more of a problem with shutter speeds of 1/60s or slower. During the ceremony I have had a 50% keeper rate at 1/10s with the 70-200mm lens at 200mm focal length and using the D4. At 1/60s the keeper percentage would have been 80% or greater.
The mass of the camera makes a very big difference in hand held shutter speed results as it dampens the camera movement. A D4 will provide more dampening mass than a D800 without the grip and with any given focal length I can go to half as fast a shutter speed without affecting my keeper rate.
The net result was that I could use either half as high an ISO setting or a smaller aperture for greater DOF in some situations. It still comes back to subject motion as being equally critical to getting sharp images.
One thing that I noticed after making the initial switch to DSLR cameras and not needing to worry about the frames left on the roll while shooting, was that I was shooting faster and not taking time to stop and brace the camera. Taking a second or two to fully stop and release the shutter only after doing so made a dramatic difference in my keeper rate as my technique was a good part of the problem.
I also started shooting at 1/80s as my minimum shutter speed most of the day when photographing weddings. Much less subject motion blurring than when I had shot at 1/60s. Most of the time people are approaching at an oblique angle and not coming straight on or moving across the frame horizontally. I just wish that Nikon had a menu option that did not stop at 1/60s as the minimum shutter speed with flash as it is not adequate for wedding photography.