Just to add some balance to this. I believe that the glass deposits will flake off with engine thermal cycles (takeoffs and shutdowns) and that any deposits in the cooling air holes will eventually work they way out over time.
Not from my experience Lomapaseo. External deposits will be fine as you say, but a couple of blocked dust holes on a blade tip and away she goes. Yes you will pick up the vane damage easier on a boro, but you will still have to open to do anything about it. I'm thinking CFM56-5 HPT vane and LP Vane 1 off the top of my head.