I've done some reading into cast iron performance and everything I've encountered says there's no noticeable difference between the smooth surfaces of the old pans and the rougher new pans once they are well seasoned. The theory is that the residue that makes a pan non-stick adheres better to the rougher surface, negating any advantage a smooth surface would have.

I've never owned an old smooth pan (mostly due to the research above) but I've noticed that over time the original rough surface of my Lodge has largely smoothed out as it has become extra seasoned.