Simops off parallel runways are one of the safest types of separation possible, essentially the aircraft are at their closest on the runaway, the rules require 210m between centrelines, to ensure separation after takeoff usually one aircraft will be on a SID that increases the lateral separation between aircraft. The departure from 34R is likely going to track over Coogee before setting course.
The biggest risk for the aircraft departing on 34 is not the aircraft on the other 34 runway but traffic on descent making an approach to the various downwind circuits for each runway. I was joining downwind for 34R abeam bondi last Monday when we had a QF 738 pass under us tracking east, it was visually quite interesting but perfectly safe with vertical separation.
