Boom blocks (pulleys) Racelite or Nautos?

So Racelite and Nautos blocks (pulleys) are both class legal. From what I have read the Racelite is a plain bearing and the Nautos blocks are ball bearings. Ball bearing blocks would seem to be superior. If you had an open choice which blocks would you get for the 2 positions on the boom for the mainsheet on a Sunfish? Is there an advantage of the plain bearing?