I have a string follow Hill and can't say that it draws any smoother or loads more slowly than my backset Hill. In fact, just the opposite. If a string follow starts with less initial tension, how can it build it slower to reach the same poundage at a given draw length as straight or setback limbs that have more initial tension? It has to build weight more quickly because there's less weight there to start.
That being said, the difference isn't great, and I suspect some folks just like the softer feel at the beginning of the draw.