I have many pictures of the same scene only differing in camera settings. To select the best of these images I often look at highlights or edges in full zoom, which I compare on the different images. While "lock zoom" works, I still have to scroll to the position after selecting another image, which can take some time if you seek special 500x500 pixels in a 5MP image.
Of course there are cases, where the image sizes don't match. I don't know what would be the "right" solution in this case. You could either reset to the top left or take the position as relative (if the view was in the bottom left in the first image, it would also be in the bottom left of the next). But this feature would mainly be intended for comparing fotographs of the same camera with the same resolution, so don't put too much "brainpower" into it
