In our company we are using both ClearCase (base) and Perforce. ClearCase is a super system but requires expertise to manage it and it is expensive. Mac support is limited (through Eclipse plugin) It allows versioning of folders too which Perforce is not able to do. A product I evaluated in the past is Plastic SCM (codice) which has all the goodies of Clearcase and Perforce (and many others); it is also much cheaper than ClearCase. Check "www.plasticscm.com". It runs on Windows, Linux and Mac OS/X