The changes did not appear to have put off those already in the scheme with 84 per cent saying they would not alter their contributions.
But Finsia chief executive Russell Thomas warned any further changes risked undermining KiwiSaver, which had already proved successful in terms of take-up in spite of being tweaked twice.
"To send a message at the outset that the levers can be so easily changed from one cycle to the next undermines confidence overall in KiwiSaver.
"This is the turning point because if the Government is seen to fiddle too regularly with the incentives that drive people to sign up then the original goals are subverted."
Finsia - which has about 700 members in this country, primarily in the banking sector - believed KiwiSaver's policy objective of shifting some of the burden of providing for retirement from the state to the private sector was a sound one.
However, unlike other finance sector figures, Thomas did not believe making KiwiSaver compulsory or even using soft compulsion was necessary or desirable.
"You either go down the compulsion route and you raise the level of contributions so it can meaningfully offset the cost of NZ Superannuation, or you have a voluntary-based scheme with compelling incentives."
Soft compulsion was "part-way between two policy goals that haven't been clearly articulated", he said.
"You've gone down a very commendable policy path and made some great inroads in four years. Stay the course, otherwise the public purse will not reap the benefits."
Officials are working on the Savings Working Group recommendation that all people working and not already members of the scheme should be enrolled while their right to opt out is preserved.
Finance Minister Bill English yesterday said the Government did not favour compulsory retirement savings because many people simply could not afford it.