The dramatic shift in emphasis had been the result of 14 months' work and was evidence-based, Gibson said.
"Harbour's purpose is 'Improving Lives, Through Rugby', and when it comes to our community we want to maximise engagement and grow participation through quality experiences.
"For us this means cultivating a climate of development and fun around our junior rugby programmes and putting the kids at the centre of the experience."
The evidence Gibson and his colleagues studied pointed to rep rugby and the prominence being given to high-performance as an impediment to participation.
As part of its review into secondary schools rugby, New Zealand Rugby released figures that showed a sharp drop-off in the numbers of school-age boys playing the national sport. One of the key reasons given for this was that teenagers quickly lost interest if they did not feel they were on a performance pathway.
Bill Wigglesworth, who leads Harbour's engagement and participation team, said the concept was not without internal debate.
"We had to challenge ourselves on whether this was the correct approach, but in the end the evidence was overwhelming," he said. "[Children] want to have fun, play with their mates, learn new skills and be supported.
"Rugby is a late specialisation sport and introducing performance and rep programmes too early can create behaviours that discourage participation in kids and have a negative impact on their physical and emotional development.
"We are not saying that performance or representative programmes are negative … this is more adjusting the current system and introducing a talent development programme at a more appropriate age."
North Harbour rugby founder and inaugural coach Peter Thorburn – who was also an ex-All Blacks selector - said he was "a bit shocked" by the move.
"At first glance, it feels like a backward step," he said, before acknowledging he hadn't seen the sums Harbour bosses were working with.
Thorburn said it was inevitable that no matter the age, players wanted to play at the highest possible level.
"We have to offer players every opportunity to progress."
Gibson knows the move will not be universally popular but hopes critics will consider the drivers behind the change, which is essentially to make rugby a more enjoyable experience for all children.
He already had indications from a "couple of parents" they would be taking their children to clubs in another union.
Harbour's stance is supported by AUT academic Simon Walters, who runs the coaching research team.
"An overriding focus on winning at an early age has a number of costs," he said. "These include closing the door on late developers and late maturers; kids not developing the all-round skills they will need later if they stay with the sport; greater rates of overuse injuries; burnout and, ultimately, dropout."
The Roller Mills is one of New Zealand Rugby's most storied tournaments. Open to northern region unions Northland, North Harbour, Counties Manukau, Thames Valley, Bay of Plenty, Waikato, King Country and Taranaki, the 94-year-old competition has a distinguished honour roll that includes several All Black legends like Grant Fox and Sir Michael Jones.
The North Harbour union was created in 1985 and has sent a team to the tournament every year since.
The fallout from Harbour's decision, given the primacy of rugby in this country, is likely to spark fierce debate.
Gibson knows that but said "ultimately we want to make rugby an even more enjoyable experience for the kids, which is the most important part of this for us".
Two years ago, Netball Mainland received flak for ending representative programmes under high school age. Critics described the move as "PC gone mad".
