Reading a teleprompter, at least to my understanding, is basically just a more high-tech way of reading something word for word. In my speech classes in high school and college, the people who read word-for-word off a piece of paper, whether they wrote it or not, were a whole lot less convincing with their "speech" than those who wrote some notes or an outline on an index card and knew what they were talking about.
If you need to read something word-for-word, it gives the impression that you don't know the material and thus can't speak intelligibly about it without that assistance. Or, if not that, it gives the impression that you're reading someone else's words/thoughts.
So, i guess i would prefer someone only used notes. To me, it makes it more believable and convincing.