You might want to try the Madcam plugin for Rhino as well, at least before you spend any money. It does not do automatic rotation of 4th axis but that is fairly easily done within Rhino itself, and I know that 4th axis is being worked on in Madcam. They have a free download for testing and support is great.
Here is a link to try. http://www.gvf.se/madcam/download_demo.asp