Sounds to me like a RD hanger. I had a bent one and could only get the chain rattle to quiet down (although not completely) was constantly messing with the barrel adjuster. Got the hanger fixed.........rides great. BTW I have a carbon Fuji, but knew it had fallen on the derailleur side.

+1 on going to different LBS. And if it turns out to be a simple fix like RD I'd go back and talk to the other owner about some compensation for all the necessary work performed by his shop.