I'm hardly calling to crucify her until the time when someone does get hurt. But it does seem more likely than not that it is only a matter of time until we are at this point. She may not have made overtures of villainy yet, but I've never read nor seen anything to indicate the opposite in Darla as a vampire.
I think Angel and Connor are letting affection blind them to what is a very legitimate risk and it does no one any service to brush it under the rug with truisms like "She'll learn to love and that will fix everything."