I own a Sherline 5400 lathe and a P/N 8760 driver box that I use mainly for metal, but have done some wood work as well. Spindle torque is more than adequate. The rapid moves with my setup are probably half that of your manual roughing cuts in the video. The finishing cuts look about the same. I'd expect the finish to be better with CNC due to the rigidity of the setup, perhaps saving you time on cleanup. Overall I think the times would be fairly similar. If it's of use to you, post a dimensional sketch of your part and I'll give you a closer estimate of the machining time.
I agree that you can increase the speed and performance somewhat by getting better drivers or using servos, however, the machine isn't really designed for high speed and the best you could hope for is maybe a doubling of what I have.