Well, now that I've bought it and tried it out, I'm going o answer my own question and say "No, it's not worth it!" With a simple scene, it crashes almost every other time I try and render in Superfly. When I tried rendering the same scene in Firefly, my whole computer crashed. I submitted a ticket several days ago, but haven't heard anything helpful back yet. (A known problem with Firefly, but nothing about my Superfly problem.)