Just had a look at the Zebra3D site.
Interestingly it looks very much like it is based on DeskProto. I have recently tried the demo of DeskProto and some of the setup dialogue boxes are identical.
Incidentally, DeskProto is a program that the OP should look at when weighing up CAM options. Real 4th axis capability. Very reasonably priced for hobby use. (read CHEAP)
Greg