Personally, I think he does very well with the teleprompter. He definitely makes the points he needs to make instead of circling all around and never quite landing on them ... something he does when speaking extemporaneously. He is great at ad libbing during his teleprompter speeches which gives them a more ad lib feel.
That being said, I don’t think he should or will give up his “rally” style of speeches - folks love it & it’s energizing. When he is dishing out the goods on Hilly however, he needs to lay out some specific details & tie it all together & I think he’s going to need the teleprompter to do it. He’s smart enough to know when to do what & he’ll mix it up.
I thought he escalated his game substantially by using one from time to time as I saw recently with the Evangelicals.
It definitely has NOT affected the sincerity of his message, or how he delivers it.