If you steal a worker twice (Two separate DoWs) in G&K you aren't stuck in permanent war, but you will never again receive a gold bonus from discovering a CS, and your influence with CS will drop faster. Also, one or more CS will have their resting point set to -20.
Translation: It's not worth it. Steal one if it's *super-convenient*, tops. And by super-convenient, I mean, you happened to be walking by, it wasn't out of your way, no one was protecting it, and it was close to home so you didn't have to escort the worker allll the way home, etc.
In my opinion, the escorting is a big issue. Having your only scout taken out of action for 10 turns to escort a worker home isn't worth it in the early game. That'll cost you big-time.
I just ignore barbarians until they steal it for me. Then you get mad influence from clearing the camp and returning the worker in the same turn.