Yes and No. Yes, if you’re an ALL-MAC shop and use the Mac OSX computer as a dedicated server to allow access to your MultiLedger company files between Mac OSX and Mac OS9 users, OSX will work fine. HOWEVER, you should not open the MultiLedger files on the OSX computer that is acting as the host, since it is not recognized as a user and corruption problems can occur.
OSX still has a problem handling “byte-range locking” requests from both Windows users and Mac users simultaneously. Until Apple supports cross-platform record locking for multi-user files, if you have both Mac and PC users accessing the same MultiLedger files, you’ll need to have the shared files on a Windows machine or Macintosh running Mac OS9.