Great post from the man himself:
But of course if you prefer a non-flat bearing, you can always swap it out. OD said somewhere a few years ago that if they put string centering bearings in their throws, a bunch of people would swap them out. And if they put flats in, a bunch of people would swap them out (and do). It comes down to people’s preference, no matter what gets put in there, people who have bearing preferences are gonna do what they’re gonna do.