a few days ago I bought the 5D3 which replaced the 5D2.
Nothing to say: EXCELLENT camera!
But I have problems in communication between the camera and Mac both with EOS Utility (2.12.3) that Lightroom 4.3: when I try to transfer photos to your Mac, sometimes the transfer works, sometimes it freezes and crashes (or better EOS Utility crashes, while LR at the end says he's not able to read the files).
Strangely this what happens if the storage format is raw, or if it is the raw along with jpg, if I use only jpg seems to happen a lot less often.
Today I tryed to do same things (photo transfer and thetering) using using a PC with windows 7 x64 and the same softwares (Lightroom 4.3 and EOS Utility): everything worked flawless.
I'm inclined to think that problems are due to incompatibility issues between Mountain Lion and camera firmware's data-transfer protocols...
Have any of you encountered similar problems?