"What I could gather from the press so far poses considerable doubt on the validity of the study," said Schneider in the emailed statement.
The study for instance overlooked the lion's share of the project's savings, almost €7 million, by not considering the licensing costs that would have been incurred when Microsoft products would have been used, Schneider said.
Furthermore, it is not true that no new software would be necessary if the city had kept using Windows, he said. "A major trigger for the decision to test the operating system architecture was precisely Microsoft's announcement that it would drop support for Windows NT," he said, adding that Windows NT was the city's standard OS at the time.
"A migration to a new operating system was therefore inevitable," Schneider said.
Munich began migrating from Windows NT to LiMux in 2006. The city hopes to have migrated 14,000 desktops to LiMux this year.
The claim that the city compared the costs for a migration to a 10-year-old version of Linux with the costs for a migration to Windows 7 is also incorrect, Schneider said. The LiMux client over the years has gradually been optimized in such a way that it is now incomparable to the version the city set out with, and the current version can easily be compared to Windows 7, Schneider added.
It is true that Munich will be unable to stop using Windows entirely because it will be unable to migrate some programs Linux. But, the claim that one in every four desktops still runs Windows is also wrong, said Schneider.
"It is true that not all business applications can be migrated to Linux," he said. But all Web-based business applications can be used without conversion costs under LiMux, and most applications that are tightly integrated with Microsoft can also be used by the Linux client with the use of other standard techniques, he added.
Currently, almost 87 percent, or 13,000 of 15,000 PCs, are migrated to LiMux, he said.
Sign up for CIO Asia eNewsletters.