I have FSD, the commute is 19.2 miles each way. I use it for about 15 highway miles and no sudden braking, passing numerous overpasses. I’ve used it on a trip to Vegas from LA, twice now, It slowed down once, but did not slam on brakes. This was done in all kinds of weather, including snow, because visibility got bad, when the window fogged up. No problem.
Have I had Sudden Braking? Yes, over the months of using it. Nothing, that scared the bejesus out of me.. yet. But it has worked. Obviously YMMV.