Planning experts who recommended Tasmania's proposed AFL stadium not go ahead have defended their report, saying criticism labelling it "opinion" was off the mark.
State parliament's upper house will on December 3 and 4 debate whether to give the green light to a $1.13 billion roofed waterfront venue in Hobart.
The stadium, backed by the governing Liberals and Labor opposition, but opposed by the Greens and some crossbenchers, is a condition of the Tasmania Devils entering the AFL and AFLW in 2028.
The approval vote could swing on two upper house independents, Bec Thomas and Dean Harriss, who haven't publicly revealed their hand.
A panel of upper house MPs on Thursday quizzed the authors of a September state planning commission report which recommended the stadium not go ahead.
The commission said the stadium was too big for the site, its costs outweighed its benefits and it would add $1.8 billion in debt to the state budget over 10 years.
Premier Jeremy Rockliff said the report massively underestimated social and economic benefits, while the stadium developer described the commission's major issues as "opinion".
Commission report author and lawyer Paul Turner said the recommendations were built on empirical evidence.
"We have sifted through the materials, we have considered the facts using our respective areas of expertise," he said.
"We have reached a conclusion which could be said to be opinions, but they are ones which are valid and which have weight."
The commission found the stadium's cost-benefit ratio was less than 0.5, meaning for every $1 spent less than a 50-cent direct benefit would be returned.
The cost-benefit analysis was conducted off information obtained via the government, Mr Turner said.
Architect and report author Shelley Penn said the stadium was assessed on its quality, including whether it was fit for purpose and on budget, rather than taste.
Prime Minister Anthony Albanese, whose government is chipping in $240 million to development at the site, on Thursday urged the upper house to vote for the stadium.
Tasmania Devils chief executive Brendon Gale has ramped up his pitch to the upper house, reiterating the team won't happen without the stadium.
"Centrally located, modern stadia with world-class accessibility and amenity aren't extravagances; they're essential community assets," he said in a presentation to MPs.
Thousands turned out at an anti-stadium protest on November 23, with a counter pro-stadium rally planned for Sunday.
