This is something I've seen on a lot of other server, mainly police focused ones though. It has its pros and cons with the main pro obviously being easy callouts for police pursuits, meetings, 999 calls etc etc and the main con being a more cluttered map. If it is done with a decent postal code map I think it could be a good addition.
rather than each individual buildings just street parts because postcode isn't different for every house but like route 68, strawberry avenue and vespucci Blvd would be great with postcodes separating the building areas as when we get a dispatch of Strawberry avenue it does take awhile to sout whole road