We tried to make OpenKM as intuitive as possible, but an advice is always welcome.
Forum rules: Please, before asking something see the documentation wiki or use the search feature of the forum. And remember we don't have a crystal ball or mental readers, so if you post about an issue tell us which OpenKM are you using and also the browser and operating system version. For more info read How to Report Bugs Effectively.
Could you guesstimate how much time will it take to implement Multi-Tenancy on a community version? For 1-2 developers.
(one week, one month, 2-3 months, 6-8 months, a full year...)
Is not only a question about time ( what might be between 2-4 weeks ), the major issue is that all the missing things you will discover after you thought you have finished with all the changes. In professional edition this change raised a lot of unexpected issues during the first months because not only has been affected the database in a lot of tables also affected the code and the behaviour of the application.