Spider distributor Question..!!!

1976 Spider. In the process of being tuned at classic garrage in Berlin. The car has a bosch distributor with a vacuum advance which since Ive had the car (16 years) has always been connected and works ! The mechanic tells me this is wrong and should not have a vacuum advance and has disconnected it. Can anyone help me with this...His he right ???

Thanks N.B.

just see how it works best- connected or not. I had a berlina with Delortto ccarbs and Marelli ? Distributor with no vacuum advance. I changed the Distributor to Bosche (to put electronic iginition) that had an advance pipe. I couldn't tell any difference between connecting or not.