I would not use on a live setup. I'm sure it will install but it would take some time to test and find any bugs. I would only install FM13 on Windows 10 Preview only for test purposes. Filemaker does not release information about future products, but they have always in the past have release updates for new OS unless they issue a new version of their software. I would wait some time even after a official release of Full blown 10 to upgrade a live working system that my business depends on.