My personal advise is not to use the Mac version of AM. I am A mac guy. I own an 8core mac and 2 mac pros. But after doing render tests with AM on the mac version I quickly realized that it is not a viable option. It can take 3 times longer or more to render the same project on the mac version of AM. Plus the Mac version of AM has a ton of bugs so does the PC version but the lessor of two evils is the PC version.
My Solution: Using boot camp install windows xp or 7 on your mac so that you can dual boot. Use Am only when booted in windows. Do not use Am on the Mac via parallels or something like that.
Although this is my opninion its based on facts: below are the bench test results apples to apples on the same system only difference is the operating system and the AM Version.
Mac time
Click to view attachmentWindows time
Click to view attachment