I don't know about you, but I have ball bearing blocks for two reasons :

-1- the run smoother when very little load is placed on them, at least that is what I think; this is attractive for the light wind days.

-2- They don't jam up as easily with sand and salt. I have a few slide bearing blocks on my boat (no ball bearing) and indeed they do easily jam up with dirt and salt and are harder to get unstuck.

Wouter