I think that the whole point of the argument (correct me if I'm wrong) is that the full frame version does show you more. The widescreen version is what was shown in the theaters, but the full frame version actually had extra picture on the top and the bottom of what was seen in theaters.

In most cases, full frame is created by chopping the sides off of the widescreen version. But in this case, the widescreen version is the version that shows less. I know that some movies are shot like this, so when they go to VHS or are shown on TV, they actually see more of the picture than they would have seen in the theater.