The people behind the Hundertwasser Wairau Maori Arts Centre (HWMAC) and the Harbourside development projects say the latest feasibility review doesn't do either of them any favours.
The review says the figures for both projects don't stack up and one of them, the Harbourside, is "high risk". It has suggested both proposals do more homework regarding operating revenues.
But both promotion groups behind the two plans say the review got it wrong.
Released this week, the peer review examines the number-crunching in two previous studies by audit and finance company Deloittes.
Wally Yovich, of Future Whangarei, behind the Harbourside proposal, said some claims in the report "are ridiculous". The review was commissioned by Whangarei District Council and carried out by Nexus Planning and Research. It looked into capital costs, funding and earnings.
Mr Yovich said the review incorrectly estimated Future Whangarei's professional fees alone to be $1 million.
"That's simply not true," he said.
Where the Harbourside proposal said it had capital cost allowances of $6.5 million, the review described its present form as a 'Partial Concept Design' that would cost a lot more.
"It is our opinion that $9.1 million would be a sufficient capital allowance to redevelop the building to accommodate an operator's business, based on current costs," the Nexus report said of Harbourside.
Barry Trass, for the Prosper Northland Trust backing HWMAC, said he was also "surprised Nexus comes along and disagrees with the figures".
His group was certain they have their numbers right, he said. Mr Trass said there was still plenty of time to put the facts to the public before next month's referendum.
The report described the estimated $13.5 million HWMAC building project as "low risk" based on the current costings.
"It is our opinion that $13.5 million would be a sufficient capital allowance to redevelop and extend the NHB Building to accommodate an operator's business, with extensive work external to the building, based on current costs." The peer review - not intended to look at the desirability of one scheme over another - also sat on the fence regarding financial viability.
"In our view, the information currently available is not sufficient to comment on the relative financial viability of the two main options because we do not accept that the available revenue forecasts are soundly based," it stated. "Despite this shortcoming, the proposals are sufficiently different to offer ratepayers a choice. We strongly suggest that more work is needed." A third proposal is to bulldoze the existing building and grass the site, for $350,000.