The only reason that the dimensions and file sizes are changing in Bob Somrak's scenario is because he is resizing. The dimensions are being forced to fit into a new ratio.
Jim Hess's explanation still stands.
Everything each of you has understood still stands.
I think that everyone is getting confused because of the different directions each person is coming from, looking at things, and the feeling that each person's point is valid; which it is.
Bob Somrak is pointing out an exception in which the units of measurement would make a difference to the ratio for resizing. But nobody was talking about resizing in the initial discussion. So, like I said, it's just an exception to the statement made by Jim Hess.