If I were you I would download the mac beta of rhino and see what you think of that. It is not complete, but it is pretty usable, and it will be free until they wrap up the beta process, which could be some time...
Rhino is not a hundred miles away from moi, and is a more mature product, so you may get what you are after without running windows etc etc

Both Rhino and Moi are fantastic products...

cheers
rabbit