Yes, it is only a hobby, but at times one gets caught up in the moment and it seems more important in the grand scheme of things than it really is. I am interested however when you say:
"Using a modern AC servo as a spindle puts you at the leading edge performance. You will, once you get it sorted and provided you remain within the torque limits of the servo have a spindle with speed/position stability the envy of many."
This implies that once you do have a accurate, controllable, spindle that more can be done with it than previously. I have seen a YouTube video of someone using parametric G Code to turn a hexagonal shape on a lathe, do you have any idea of this?