It has a really big effect I think on the tone of what gets selected at the top. The lower bound prefers things that are preferred by a majority and very popular. The prior method prefers things that are completely un-objectionable and liked by just enough people to be sure of that. My hunch is that with the lower bound you get more interesting things bubbling to the top because it puts a stronger emphasis on popularity.
In all of these models, the giant variable that is completely ignored is the actual choice to rate something at all, versus skipping over it and reading the next one. That's a very significant decision that the user makes. The behavior of each of these systems w.r.t that effect will be the dominant thing differentiating them.