Hi Burr, the revolve method is certainly a fine surface, but not quite exactly the same shape as the other ones, if you look from the side:



You can see that the side-view profile of the surface does not quite match that middle rail.

But if you want a nicely formed rounded tip and don't mind about such exact control over that "down the middle" profile curve, then rail revolve is a great way to get a rounded shape and it has an advantage that it uses a small number of curves to define it.

- Michael