1. Have 2 clients, one on persistence and one to not
  2. Create an instance, have your non-beta friend join first
  3. Join from beta
  4. Be kicked for "World version incompatible with this instance"
This does not occur when the first person in the instance has persistence enabled. I have not tested what happens if the first player in the instance is a persistence beta user, non-beta joins, beta rejoins (master transfer to non-beta)