This week I was talking with a client that is a photographer. She just had sold a 3 feet x 6 feet print. When I asked which camera was used to take the shot she said D300. There are many ways to improve definition and enlarge when you need to. But in real life, except for commercial bill board photographers, 12, 16, 24, 36 MPs are quite enough. When you go above that, it's the lenses that will not be able to follow the sharpness.
Oh, I was forgetting, a picture is not all about how sharp it is, neither about which camera it was taken with, it's about the image itself and the light and composition that made it, and the photographer that was there who saw the picture an instant before he took it.
Again, just my opinion.