I don't think that on smaller screen sizes you will really get the benefit of a 1080 source. I think looking at the downscaled 1080 -> 480 images on that site you'll see you can't really get a grasp of how much detail is in those pictures. It looks better yes, but it looks a lot better when you can see the image at its native resolution.
I'm also pretty sure that watching a 1080p movie on a 720p set won't result in any better picture quality.