MikeR, sorry no one has gotten back to you on this thread. Usually the author of REW will respond to the MAC question, since I'm so un-educated in that regard. I'll send him a note and see if he can help out.
Either way, there are problems with the MAC running REW, although the latest version (in beta testing) is somewhat better. Perhaps John will be able to send you a copy. I do know that we have very positive reports from people running Leopard operating system who use REW.
brucek