The change meant voluntary redundancy for 4.2 full-time equivalent mental health support workers.
Pact also wants to cut the time clients spend in the facility.
Pact chief executive Louise Carr said night carers would be provided for the first six weeks at the Helensburgh Rd units, to which clients would start shifting next Wednesday.
After the six weeks, help would be "on call" until 7am after the last shift finished at 11pm, but not on-site.
Night carers were retained for Pact's higher-needs clients, who were not involved with the new facility, the changes or restructuring.
The 41 units were bought from the Dunedin City Council in January by Pact's sister trust, Ladder Trust, of which Mrs Carr is also chief executive.
The trust leased 22 units to Pact, while the remainder would be refurbished, as funds allowed, for social housing for those needing a "hand up" for the short- to medium-term.
The remaining 15 DCC-era tenants could stay as long as they liked.
Mrs Carr hoped the mix of different people would engender a village atmosphere in the former council flats.
Residents had privacy in the single flats, but could enjoy a communal aspect in the well-designed facility, she said.
All 41 units would share a community lounge.
Significant resources had been put into refurbishment, and Pact was proud of the improvements.
The purchase was an excellent opportunity to achieve the economies of scale of an institution without being an institution, Mrs Carr said.
The units replaced facilities in Norwood St, Musselburgh Rise and Centennial Ave.
Supported accommodation service manager Thomas Cardy acknowledged Pact wanted to reduce the length of clients' stays. He declined to give specific timeframes.
Increased support with focus on independence, budgeting and work skills would help people return to the community sooner.
"We're not talking about pushing people out the door."
Pact had been "over-delivering" on its contract and wasting taxpayers' money on the extra service, he said.
He believed Pact had "alleviated" the Southern District Health Board's concern about the loss of night carers for some clients for whom there was particular concern.
Southern DHB mental health and community services general manager Elaine Chisnall issued a statement by email saying staff were working with Pact on the changes.
"The [DHB] mental health service identified a couple of issues with the changes Pact were making and these were raised directly with Pact at that time.
"Clinical staff members of the community mental health service are continuing to work collaboratively with Pact to develop plans to meet shared clients' needs."
