I've got a vision-only model Y. I don't know how good the radar-based ones are, but I do know the vision-based adaptive cruise isn't great. Does a fairly poor job of maintaining a consistent distance to the car ahead, compared to other cars I've driven. I also had to turn the automatic emergency braking to its minimum sensitivity setting after it slammed on the brakes a couple times for no reason.

So I don't know if the radar-based was better, but the vision-based isn't very good imo. (FWIW the vehicle's been great otherwise.)

Do you have a source for this? I'm only seeing that the radar permanently stops working if you opt in to FSD, with no way to reactivate it. But this only happens if you enable FSD.