Some ball pythons just won't accept live. Some won't even eat if you're watching. What's best and safest isn't always possible if you want to keep your ball python alive and healthy.

If you can switch them to FT, then FT is obviously safer. If you can't...well, then, you have to feed PK or live. No sense in fretting over it, nor any sense in misleading newbies to believe that ALL snakes will take FT, and they just need to be patient. I've seen excessive 'patience' kill snakes through starvation before.