I guess what I was really saying is that if the 5D had no only offered FF and more pixels, but also higher pixel density,.. (ie it would have needed to be more than 12MP) I might have been more interested. For getting detail of birds in a long telephoto, Pixel density ends up being one of the most important aspects.
Since the 5D was offering the same pixel density as the camera I was already shooting, but with less capable AF and frame rates etc.. it wasn't an important camera to me.