Cresteds tend to calm down and jump less as they get older, I'd imagine that gargs are similar. Cresteds generally handle being held well but I have heard that gargs are generally even better with being held. However both have individuals that are calmer or flightier than the norm.
On a side note, after this coming Sat. my knowledge of gargoyles will no longer be theoretical! Broke down and bought a baby from a breeder in Utah, will be meeting up with her on Sat. to pick it up. Can't wait!