The Bureau of Transport Statistics have released ferry patronage data. It seems that the iconic Manly ferries actually experience their peak patronage outside of what is normally considered peak hour. In fact the Manly ferries peak at 83% of seated loaded in the morning peak. Given that the ferries only come approximately every half an hour, it seems clear that these add only modest value as a commuter service. There is a sizable number of people making a commute from the area near the wharf, most notably on the E65 bus. There is no reasonable feeder bus service to the ferry wharf and using the reasonable speed catamaran ferries (around 18 minutes to Circular Quay) would mean that you can't use a MyMulti for the combined journey.
Time the Freshwater class vessels were retired and the fast ferries included in MyZone fares, running more frequently.