Washington (CNN) -- Despite the upbeat tone of Pentagon leaders and authors of the report backing a repeal of "don't ask, don't tell," the data released in conjunction with Tuesday's report shows that a substantial fraction of military personnel have concerns about the change.
The full 256-page report from the Pentagon working group found that most military personnel would not change their career plans if the don't-ask-don't-tell policy changed. But almost one in four said that repeal would mean they would "definitely" leave sooner than planned or think about leaving sooner if the rules were changed.
The authors of the report, Army Gen. Carter Ham and Pentagon General Counsel Jeh Johnson, emphasized that predictions won't always translate into concrete plans, and that some people's attitudes were based on stereotypes or misinformation that could be changed through education and training.
The Pentagon carefully controlled the release of the report, allowing journalists to see only a short executive summary prior to an afternoon news conference by Defense Secretary Robert Gates and Joint Chiefs Chairman Adm. Mike Mullen. Journalists were allowed into a Pentagon conference room and handed a numbered copy of the summary which had to be returned when they left. The actual report -- two volumes with 87 and 256 pages -- wasn't released until after Gates and Mullen had spoken and the report's authors had answered questions.
The report shows in detail how much higher the opposition to the policy change is in predominantly male combat units, including the Marines and Special Forces.
"While only 30 percent of the U.S. military as a whole predict negative or very negative effects on their unit's ability to 'work together to get the job done,' the percentage is 43 percent for Marine Corps, 48 percent within Army combat arms units and 58 percent within Marine combat units," the report found.
The authors say those higher numbers can be traced back to attitudes, with substantially fewer people in war-fighting units having served with someone they believe to be gay.
"More are left to only imagine what service with an openly gay person would be like -- the circumstances in which misperceptions and stereotypes fill the void, for lack of actual experience," they say in the report.
More than 44 percent of military personnel with combat experience since 9/11 say if they are working with an openly homosexual service member, it would have a negative or very negative impact on the unit's effectiveness at completing its mission, according to the report.
That falls to 29 percent when a crisis or negative event happens and is about 30 percent in a hypothetical "intense combat situation."
And while 43 percent say working with an openly gay or lesbian person in "your immediate unit" would have no effect on morale, almost 28 percent say it would affect morale negatively or very negatively.
Defense Secretary Robert Gates made the point repeatedly that the Pentagon will take steps to train and prepare the U.S. military to cope with the changes.
"I am determined to see that if the law is repealed, the changes are implemented in such a way as to minimize any negative impact on the morale, cohesion and effectiveness of combat units that are deployed, about to deploy to the front lines," Gates said.
But the report's quotes from military personnel opposed to and in favor of repeal and show deep divisions about the issue.
"I cannot rely on someone who I don't feel comfortable with, nor can they trust me. A lack of trust turns into a lack of cohesion which eventually leads to mission failure," says a quote from one service member who made the comment online..
"I cannot tolerate homosexuality," says another anonymous comment in the report. "I will not work side by side with someone that is an adulterer, a drug addict or a homosexual."
"I strongly disagree with the repeal of the Don't Ask, Don't Tell policy," says another online comment included in the report. "I believe it will cause more conflict and more hazing among the military. It seems to be working perfectly as is."
Another online comment came from a person identifying himself as a Battalion Commander for a unit just back from a 12-month combat deployment in Iraq. "I can say unequivocally that gay/lesbian soldiers are integrated across our force, at the lowest tactical levels, with no negative operational impacts."
And gays and lesbians serving already told how they would welcome the change. "I doubt I would run down the street yelling 'I'm out;' but it would take a knife out of my back I have had for a long time. You have no idea what it is like to have to serve in silence."
The report said some of the most "intense and sharpest divergence of views" about "don't ask, don't tell" came from the chaplain corps.
"A large number of military chaplains (and their followers) believe that homosexuality is a sin and an abomination, and that they are required by God to condemn it as such," according to the report.
Gates said no one would be asked to teach something he or she didn't believe in.
"The chaplains already serve in a force, many of whose members do not share their values, who do not share their beliefs, and there is an obligation to care for all," Gates said.