If you knew how easily reared and abundant Berghia were, you would not care about them dying when the job is done. They are just like Xenia, Star Polyps, or Chaeto.
The fate of many snails and hermits makes the Berghia deal seem miniscule.
The price is the thing that makes ya pucker... Yeooow !
Go with the Shrimp. They gang up on the bigger ones when the run out of the smaller ones. They act as a preventative too.
I REALLY like Aiptasia Control by Blue Vet Rx, it's like joes juice but actually works. It comes out like tooth paste, not all watery. A little goes a long way and it definatly kills aips in seconds.