It's like looking at a painting on a wall. The farther away you stand the more 'photographic/detailed' it becomes. The closer you stand the more fuzzy it becomes.
barnes has got the goods... its not the same, but its going to turn out to be similar visually. ..not in that the image will be the same in result, but the basic overall increase in percieved quality by the veiewer will be pretty much indifferent. like inhaling mace- or inhaling pepper spray.. they are different .. but really have the same effect. the one drawback from the sharpening of the native resolution is as j. barens pointed out ..you may get sharpening artifacts..such as increased noise, and grain. the downconvert will not have these issues introduced ..assuming they were not there to begin with.