Ok, lets throw in some first hand information. Right now I'm running an older G4, OS 10, and Illustrator 10. Cutting Master cuts directly from Illy. It's a plug in, not a "bridge" application, and it works just fine. I ran it on OS 9 on a G4 also. I am also running it on my MacPro, OS 10.5.8 and Illy CS3.
On the G4 you will need a serial to USB converter though.
On the newer Macs it runs fine as straight USB connection. In fact, I have both my workstations connected to my Graphtec fc7000-100 at the same time and can cut directly from either one without changing a thing.